I would have responded much like the second lady (telling him I would call the police). If he is not going to follow the rules of the dog park by keeping his dog under control then he would have to leave. I am not shy about calling the police to enforce the rules at the municipal dog park. Trust me, make a big enough stink and they will make him leave. I have no problem being Miss B***h when dogs or people could be hurt by an irresponsible dog owner.