^^ pod Twik
in my school year 6 at primary (5-11yrs old) we had a child with yellow syndrome, they were lovely but if they got over excited or over stimulated it could cause a major meltdown, this was just how they reacted. the teacher had a learning support assistant who worked with the child and knew what signs to look out for, as did the teacher.
one week we had a sub teacher who thought they knew it all, when LSA started to take child out of situations that were over stimulating the sub refused to allow it and was responsible (i was 10 and have no doubt it was down to them) for the child injuring themselves.
that sub was written up and never allowed to come back to our school, the parents knew it was not the schools fault and never thought of litigation (i learnt a few years later as friend of the family)
it takes a lot of time and work to learn about different conditions, purple could very well be one that doesn't react well to be touched by non family or untrusted people.
OP i think the school owe you an apology, not the other way around.