I understand the difference, and in some respects your obviously right. I’m not trying to make the case that being elderly is like being autistic. Heck, I’d be slamming myself with thoughts like that.
What I am addressing is diminished capacity.
Both the autistic person and an elderly person have reasons for their bouts of anger. Neither are particularly justified. To them it sure is.
My grandparents ran a nursing home. Every once in a while a client would get angry because someone stole their socks, or their shirt, their pillow, or even their tools they hadn’t had for a decade or more.
The autistic person has an equally reasonable (to them) issue that sets them off.
And you’re right, the elderly person isn’t generally going to bite someone. They may take a swing at someone, if they’re of a mind to.
There are a number of reasons that an elderly person may be prone to anger, such as Alzheimer’s and other forms of dementia.
My mother tried to stomp me with her walker this summer because she didn't like the way we were moving her into her assisted living apartment.