People haven't ignored your post on purpose. I think, they don't know what to suggest. Your problem appears complex.

I read your post shortly after you posted it, but did not know how to respond. I still don't, because I don't have an autistic sibling nor have I heard of the behaviour you described in autistic adults. All the autistic people I know are high functioning so I have no experience with this.

The only thing I can say is your brother continues to pout, because it works. I have no idea how to fix this behavior so I cannot make any recommendations. Sorry.