Well, I was assuming you had not met before and if so the conversation of the dogs behavior and being loose would have been quick and to the point. I know I would be shamed if I failed to secure my dogs for everyones safety including the dogs. Of course having animal control make a visit is always an option. I know you are trying to be nice about it, and all. But if you felt like the dog is a threat, treat it as one. I know that I would shake the hand of anyone who shot one of my dogs if they attacked and if I failed to do my duty as a pet owner.
I once had a neighbor with two big lab mixes that would get our and run the neighborhood. They weren’t nice labs and were agressive.
I didn’t do anything except be careful and watch my kids closely. One day they cornered my wife in our garage. Turned out ok but I’ll never be nice about dangerous dogs again.