He absolutely did the right thing.
Agreed, because no parent was present. I'd be over there inviting them to a bbq so fast that it'd make a ninny dizzy (sic). It's a very neighborly thing to do and We, the People, have no one but ourselves to depend on, and it's good to make friends and help your fellow man.
I counter your paranoia of she might freak, with how do you know that they aren't at this minute considering getting their first gun for home protection or the poor political climate? Just like aaron takes newbies shooting from his work and watering hole, we all must make an effort to be friendly and helpful and kind (don't forget to smile). Just be cool and make an effort. They're not going to throw you in jail! Oh my Gosh...
Quit being a scaredy cat and go invite them to dinner. Don't just knock on the door and say hey can I let your kid shoot my gun. Then you might freak them out. Be neighborly about it.