No, I know what you were saying. It must be so difficult for those kids who are purposely being wound up then they get the blame when it becomes too much. I believe my sons dad was on the spectrum, and he was labelled 'thick' and 'trouble' at school and by his own mum! She was always telling him he was too thick or stupid to do anything he wanted to do, career wise. I think that's incredibly sad, because I think those on the spectrum can be so gifted. My son we believe has Aspergers, and he is so knowledgable on certain things it blows my mind! And many others too! He went through a stage of violent outbursts but I believe that was down to him trying to cope with the grief of losing his dad.
Not everyone is violent by any means. I know a kid who lives a few doors down from us and he struggles with anger, he's flown into a rage a few times but it was always provoked. He never flies off the handle over nothing.
But yeah you're right absolutely that whilst someone may not at times be able to help their actions, it doesn't excuse violence because it is totally unacceptable, but I think the OPs brother could do with a little help to see this himself. It would be a shame if he landed himself in serious trouble. I guess it really does depend on the severity of the disorder, like you say.