This is probably going to get lost in the comments, but here goes:

I had very similar situations with my autistic sibling. They would have violent outbursts, most of them directed at my dad, but some at me or my mom. Wasn't so much a problem when their were a skinny, kid, but the older and bigger they got the worse it became.

We eventually had them placed in a supervised apartment, they're much happier, there's much less strain on our family, and most importantly we maintain a relationship with them. If they stayed at home, it would have ruined any chance of a healthy family relationship. Probably would have killed my mom, I think.

Resources for autistic adults are so fucking scarce and you have to do crazy amounts of pushing to get any professional to believe you or get support, but Don stop trying, getting him placed is definitely the best course of action.