Is this bullying? Would you intervene?

[Cofeeandagoodbook]

My son is yr5 age 10 with a diagnosis of adhd and autism. There is a boy at school who has low level picked on him for years. Its not every day but has recently become more frequent. Examples -
they have friends in common and when playing tag in a big group the kid will call over the others and say let’s all get DS.

if my DS is with a good friend of his, that this boy is also friends with, the boy will come over and say play with me not him or I won’t play with you later on Roblox

he make comments to Ds like you’re the reason this friendship group is ruined

pushes him out of the line for assembly and takes him place so DS is at the end/alone

he is quite good at riling others up to agree with him

my son if not good at sticking up for himself. And he doesn’t easily trust the teachers as they’ve dismissed him when he has tried to explain the issue in the past. The boy is well liked by teachers who have taught his elder siblings.

my ds has sobbed this evening. It’s frequent at the moment and really getting on top of him. I have encouraged him to speak to someone at school.

Is this bullying? Would you as a parent have a word with school?

What does he want from you? I guess it's always hard to support at that age without undermining.
I am familiar with these conversations, what's good is he has the confidence to talk with you . This is a great strength so many keep it in. I'm sure you do but that's worth telling him.
The lowest level of support is listening, and encouraging him to consider strategies. Does he for example feel he can discuss it with any other child. This child he complains about sounds kind of insecure and the chances are others have experienced similar. Can the emphasis come off this child onto other better friendships and how might you promote those? Playdates perhaps? .
Does he do anything out of school that can build his confidence.
Just some thoughts but I do feel for you it's tough when you can't just leap in and sort it. Talking to teachers is an option. They are possibly completely oblivious to how unhappy he is. There might be lunchtime groups he can join to get his own space /.ways they can re arrange classes.

Thank you for replying. It’s a good shout to ask him what he wants. He has asked me to speak to school which I’ve done this morning, I’ve given them some context and asked them to get him an opportunity to chat it through with a teacher he trusts. He possibly needs more time and space to communicate than some children and so that is something I can advocate for.
it’s heartbreaking to hear him talking so negatively about himself and he’s at the age where peer relationships maybe have more impact. Any advice on how to support with his slef esteem?
he is a part of clubs and have friends who he has play dates with etc.

Aw I'm glad he has trusted you enough to let you help you must have a brilliant relationship. That's the thing which will help him. Other than that - anything he is good at or succeeds at is likely to build confidence - or learning a new skill-
School could be enlisted as well-
I've noticed some parents are very good at utilising the support of schools for things like this.
You are best placed to know, what will work for him. But we are all doing trial.and error to a certain extent.
I'm glad you have talked to school. I left it too long and did it in the end anyway, and wished I'd done it sooner. Now he knows he is being taken seriously. Good luck with it all.