I mean, at the core of it he's in the right on several levels. He has a moral obligation, he has rules and regulations tying his hands, but the thing is it seems pretty clear that he's not actually tried to communicate with Vista on these things. If he has at some point got down, sat down full seriousness with Vista, explained to her exactly what the problems are and discussed how to meet in the middle, I'd respect that at least, but...
From how it sounds, taking both their testimonies into account, It sounds to me like Chevalier has been making declarations without any explanation and with no attempt to find any sort of compromise. He's just going 'my way or the highway' and putting everyone else before Vista on the sole basis that she's a problem, which is frankly the exact opposite of what you want to do.
Work more closely with problems to try and help them stop being problems. Don't push them away, it only makes everything worse.