Should I be proud or angry??

This is sound advice.

Personally I would be proud of my child for putting a racist bully in their place. Absolutely no need for racism it's disgusting. Sometimes action is the only way to deal with a bully unfortunately (may not be right but needs must when defending yourself).
That being said I would be having a good word with your son to explain the consequences of hitting someone on the head which he should know. That could have killed or seriously injured the other boy and your son would have that on him. People trained in martial arts can be charged as their body can be classed as a weapon. He could have used a different tactic which didn't involve kicking a head. He could also loose his license.
All people have their limits but I would absolutely be backing my child in this situation. Seems like the school have done nothing to protect him from this but he gets punished when he finally snaps. That's not right either and happens all to often.

I had a rule with my DDs that if they used their karate skills on anyone, they would have to explain and justify it to their karate teacher. If the karate teacher agreed it was the correct action and justified then I would do everything in my power to ensure no other repercussions happened.

DD1 had been bullied by a boy at school over an incident he falsified - he told everyone she'd kicked his dog to death - the dog launched at her and bounced off her foot, witnessed by his mother who's a friend.

We were at a park with a passel of kids and the boy shoved DD aggressively, and when the boy went to do it again she performed an excellent kick to his chest and launched him backwards. She took the opportunity to run away and get an obstacle between them. His mother and I took control of the situation.

She told her teacher, and that was the end of it for us, as the teacher said she'd done exactly what her training was for. Depending on the situation, and if you are confident your son followed all of the training, I'd do the same here and feedback to the school that you consider the matter closed.

you haven;t paid all that money for nothing

I don't think that it helps to connect racism & bullying, it tries to justify something unacceptable in an unacceptable way - i.e. bullying is always unacceptable, racism is always unacceptable, this scenario is always unacceptable whatever spin you want to put on things.

Be proud and dont punish. Black belts can cobtrol kicks thats why they black belts. Shame on school. Its a lesson now to all the others kids stay away. Hes a hero cos the other kids know hes a vile bully.

I felt sad for your son reading the post. He sounds like a lovely young man dealing with things he shouldn't have to. School are failing him.

Its"kinda unreasonable" to imply that i said anything about who was to blame.

You keep thinking that a shove that may cause a fall is equal to a kick to the head and I'll keep calling bullshit

I’d be proud too. F* the school and what the head thinks - real life is much more than just school. Your son stood up for himself, I’d be proud. The other boy may think twice before he starts on anyone else now.

That is classic behaviour to deny racism and racist violence.

again:

blackequityorg.com/who-we-are/

Agreed.

It is a mistake to think your son had the ability to careful control what harm was done. It's just luck. There's an episode of 24 Hours where a previously decent boy kills someone with one punch. The police involved all talk of their mixed feelings about it. That could be your ds.

It is utterly unacceptable for your ds to he subject to racist harassment at school. But there are many other ways to sort it and outside of school if your ds tries to sort issues with violence he will be in a very difficult place re consequences very quickly.

I'd 100% be proud of him and back him all the way at that school. That bully has played a stupid game and won himself a stupid prize.

The other boy earned it, well done to your son!

"The other day however, this boy shoved him hard (not just according to DS, multiple witnesses also) against his locker and called him a horrible racial slur [...]."

As a stand alone event this would enrage me. However, this is the most recent of many incidents. The perpetrator is not just a bully. He is a violent racist that has been assaulting OP's son with impunity. I would be putting that to the school administration and asking why they have turned a blind eye, or even sanctioned such behaviour.

@Seymorbutts Please get outside advice. Don't let the racial aspect slide.

blackequityorg.com/who-we-are/

It's understandable why your son reacted in that way but I would talk to him about the consequences of using violence unless his life is under real threat that knocks someone to the ground.

The risk isn't the kick, con it's the landing. All it takes is a bad crack to the head on a hard floor, a kerb or furniture as you go down and you may have a cerebral haemorrhage and a dead child.

There are literally legions of manslaughter and murder cases like this where a punch results in a fall, a head injury and death and good people whose lives are ruined forever.

Your son sounds like a good kid. He's been lucky this time but you don't want him in jail.

He did the right thing, and I'd be asking the governors and appropriate staff for answers to why a child should be suspended for a single act of self-defence when violent and racially aggravated bullying results in nothing at all. I'd arm myself with the relevant part of the school's policy on bullying and racism on premises.

Please tell your son that he's an example, and that a random middle-aged woman thousands of miles away is proud of him for showing skilled restraint and control when provoked. And congrats on the black belt.

A shove causing a fall can kill .... end of. (Which was done to the victim of the racist bullying.)

The son is the victim here, not his bully; blaming the victim for something which did not happen is kinda unreasonable.

You can keep arguing with me but you won't change my opinion.

If the son was injured then the racist would have been in front of a judge. That's the law.

Personally, I wouldn't want my son to be provoked into risking their entire life & future that way.

And actually I haven't said he was wrong to put the bully on the floor, just that he's capable of doing so safely, so he should have done it safely.

A controlled kick to the head is still a kick to the head, and no kick to the head is safe.

I can sympathise that your son finally snapped, and give him some compassionate understanding for that. However, a kick to the head can kill. One kick or punch can kill. Then your son would be in a whole different situation with lifelong ramifications.

What absolute bullshit.

A kick to the head can kill....end of

I'd be proud, yes and furious that the school have not safeguarded your son before when they knew he was being bullied.

I think the advice years ago, about being kind, not responding, and reporting bullying to the school authorities is just not working. I believe, and this may be an unpopular opinion, that if children don’t strike back the bullying never stops. If I had a child, I’d be preparing them to stand up for themselves, and not shrink away. Schools can’t cope, it’s every child for themselves or in therapy in later life.

Support. Your. Son.
It was self-defence.

All those catastrophising about what didn't happen, all the incidents where DS was tripped over and shove could have had the same result
I think @SinnerBoy makes a very good point, all of the assaults on the OP's son could have led to serious harm, yet no-one seems to be bothered about that!

And if the son had been injured? Which is at least as likely.