I would personally be honest with him / them. I'd tell them that although I love dogs, there are laws in place. And God forbid the"nice" pitty ever does anything, they will be accountable. Then reinstate how I don't want their dog in my yard. If it turned to a pissing match, I'd call the bylaw in on them.
P.S. I love dogs and I know many pitbulls. So the breed does not bother me. But dogs are dogs.
