YANBU.
So if he doesn't need "lectures about looking after disabled people", it certainly sounds like he could do with one on why the concept of "looking after" is patronising to citizens with equal rights.
I can understand it's a sensitive point for him, but surely he can see that his experiences as a parent of a young child don't necessarily equip him for knowing everything about every disabled person ever?
As my DMIL says, her experiences as a parent to her disabled DD, equip her to know a bit about being parent to her DD. It doesn't mean she could make up national policy with no need for comment from anybody else.