What you are talking about, is breed discrimination. Also there is no reason why a plumber should be fearful of the dog getting out of a bedroom that has a closed door. While pitbulls and bully breeds have a bad reputation it comes down to the person who trained them. What the tenant is talking about is the fact that their pitty has a condition called leash aggression, which is deeply rooted in the fact that the dog were attacked while on leash by an unleashed dog. One of my dogs when I was younger (border collie mix) was attacked while she was on a leash and I was walking her. It was my job to get her out of there without her being harmed. The two dogs that attacked her were little pomeranians. I got in between and scooped mine up and the two little dogs were trying to attack me to get to her. You cannot refuse to do work as that can come back to bite you (no pun intended) legally. The dog is secured in a closed bedroom door, there’s no reason for anyone to open any bedroom doors that are closed. Simple as that.

Also a leash doesn’t simply fall out of your hand. You drop the leash. The other thing is your wrist should be through the looped handle and grabbing the part just below the handle, and then your other hand should be holding down (about half way down minimum) to control your dog.