If he doesn't trust him, he probably just shouldn't roll with him. It also raises the question of why the coach of the gym hasn't intervened if the guy in question is a dangerous partner to those around him. The reason I have an issue with people that dictate some special terms to rolls is because usually they tend to go the hardest.
"Oh man, my right shoulder was hurt two weeks, ago so be careful", what am I supposed to do with that? How do I avoid the entire right half of your upper body - sure, I can not go for Kimuras, but it just seems odd. I feel like it would be much better to just drill if something on your body isn't feeling up to par for sparring.
I know that I'm projecting on everyone though my own anecdotal experiences, which is a dangerous thought process, but it seems to be a type. By that I mean, the people that ask you to refrain from something, are usually going to smash cross faces, knee on face, and generally act like this is the final match of a tournament.
The 'good partners' are the ones that don't mention anything beforehand but tap when they're in a compromising position or beginning of a hold to mitigate any exposure of their injury.
