Similar happened to my son is secondary.
The boy is question tipped yoghurt down his back on his 2nd day there but they said no proof do nothing happened.
2 weeks later I got texts from him stick in the toilet after PE by some kids throwing his stuff at him and him too scared to leave (was on transport as ehcp).
Yet - somehow - he managed to be the calling the original kid a racist name at the same time. Reported by other pupils. He was punished severely.
Didn't matter apparently that he couldn't possibly have been calling the kid a racist name in maths when he was in a completely different class (PE) at the time. And of course him being bullied was never investigated.
They have to react to any racism claims full stop and report. Seems they can't take a view of investigations actual facts.
2 years later the same children called him a spastic cunt on kahoot in public. It was after calling him autism boy and being warned, then spastic autism boy and being threatened with detention and removal. (Ds has a MND and is autistic)
They were removed from the kahoot session and given a detention.
I had to send a VERY strongly worded email about their discrimination towards people with different protected characteristics.
I threatened going to the police and reporting it as a hate crime unless they received equal punishments to DS for doing something that wasn't witnessed that he wasn't even present for. (Luckily because they were using their phones for kahoot ds managed to get a screenshot).
I think everything should be investigated and taken EXTREMELY seriously. But there has to be a point we don't apply intentionality where it doesn't exist and where there's evidence it couldn't have happened then it's treated properly.
My ds was still affected by being accused of racism years later as he couldn't understand how he could be punished for something the school even admitted he couldn't have been present for based solely on the fact they had to react because it was reported. 