Would you consider domestic violence with younger siblings less valid?

So this stems from when a younger sibling acts up and hurts their older sibling they get away with it because they are younger. Even if the younger sibling is physically larger and stronger. Here are some examples.

I know a family where the younger daughter is an absolute menace. She screams and will throw stuff at her older sister. But her punishments are minuscule compared to what the older sister gets if she fights back. 2 year difference. The younger sister is physically smaller.

In my own family my younger brother used to beat at me when he was angry. Yet he has autism so he has that excuse but people would say he just doesn’t know better and not do anything. I want to point out he was at least 50 pounds more than me and big. I’ve seen other cases of younger autistic brothers hitting their physically smaller older sisters when enraged. 3 1/2 year difference between me and brother.

Do you think just because they are younger they should get a pass? Should this be taken more seriously. Does it depend on the age difference? Should it depend on size.