Assuming the range handles it properly (as in, doesn't hand each kid a gun and then turn them loose, which I can't imagine happening for insurance reasons alone among other) then i'd be fine with it. Heck, I'd attend and join in if invited. I didn't grow up with guns, and only shot one for the first time this year, but since meeting my DB (total redneck, lol) I've learned how fun it is and have come to really enjoy it.
In fact, this sounds like the kind of party DB would want to have for his kids, should he have any. We spend a lot of time out at ranges here with our friends. We're actually headed out Saturday morning because my parents bought him a bunch of new target for Christmas. It's a hobby, and a sport, and fun. I've seen all sorts of different people out there, ranging from young macho guys, to whole families with young children.
I don't understand the "my kids won't interact with kids who's parents own/use guns" mentality. Just because someone owns a gun or enjoys the sport, doesn't mean they have a loaded assault rifle laying on the couch with the safety off. Do parents go into each new friends house and search it top to bottom before their kid is allowed to play? Or are we supposed to put a sign in the window? Point being, that seems like an odd statement to make, because unless that's one of the first questions you (general you) ask everyone you meet, or really do search friend's homes...how can you be sure? You could come to my apartment, bring your kids, have dinner, socialize for hours, and leave without ever knowing there were 3 rifles here. They aren't visible, and we don't go around pointing them out or talking about their presence.