I would not be wanting to hang around with children who are permitted to ruin trips out.
I say that as a mum who has removed my overwhelmed autistic child on many occasions. There's no point in letting him ruin a film for 20 minutes, he's not enjoying it, I'm not enjoying it, no one else in the room is enjoying it, so a swift exit is the answer, as frustrating as that is.
My first action would be to be selective about where we go to avoid situations that the child doesn't cope with. With my own child, even as a teenager, a "nice" meal out is something predictable and formulaic like Nandos or an Indian or Chinese. There is no point attempting anything fancy where he'll start panicking over not knowing what something means on the menu. When meeting other families, something active like soft play and walks always worked best. They could vent energy and they could choose between being sociable or doing their on thing.
I would not be mixing my baby with violent poky child. There's no point in socially meeting in that combination if I'm having to double parent my own children and watch out for a poorly parented child that will harm mine. The child's parents need to be hawk-like with him.
If these are friends that you've met solely through having children of similar age and there's nothing else to bind you together without the children, then incompatible parenting values are something worth letting the friendships slide over. I can't enjoy time with people who will let their children ruin other peoples' experience or cause harm.
If they are trying and struggling despite doing their best, that is different.
What kind of message do you want to send to your children about friendships? Are these friendships the type that you'd want your children to make in school? How do you want your childrens' school friends to treat them?
I'm not a smug parent (child last escorted out of McDonalds at age 11 because he was brewing for a meltdown, and no body went to McDonalds to listen to him escalating from grumbling mood to rage mode- staying would have done no one, including him any favours), I'm just a tired parent who'd rather have a few good quality friends compatible with my family's needs than to compromise my child's coping zone or feel compromised by other peoples' less than half-arsed efforts at parenting (and I encounter plenty enough of them at my youth groups...)