If you didn't put in your note to the management company that the husband said the dog would eat your cat and the wife told you not to talk to her when she's walking him, I would document that. If the dog were to bite someone, the fact that they knew he was dangerous would not work in their favor.
Unfortunately, it doesn't sound like these people have an appropriate living situation for this dog. While your goal is not to make them get rid of the dog somehow, I don't think you should let this drop. If their dog is aggressive, they simply should not take him out in public. Yes, dogs need exercise, but the entire complex shouldn't suffer so that could happen. If that means they need to rehome the dog, so be it. They really should have thought of this before rescuing an aggressive dog. I'm actually surprised a rescue let them have an aggressive dog in this type of living situation.