You talking about a restaurant that looks like this?
I probably wouldn't have said anything as it looks like a kid friendly restaurant and I'd expect a group of kids with shit parents to act out. Either accept that or go to a better restaurant.
However, if an old lady started lecturing me I'd be respectful and leave her alone. If a guy were to tell me he didn't want to see me at chuy's again I'd laugh and otherwise ignore him.
No offense but usually when people tell stories like the one you've told they either intentionally leave out half the story or unconsciously do so because they're personally unable to accept responsibility for their actions. This is somewhat of a self-selecting problem because the kind of person who would write a tldr story of them staring down a retarded family would also be unlikely to recognize their part in the problem.