He's... an employee. Not a die hard fan lol. If this was included in the contract then yea, he deserves getting sacked since he went back on the agreement but otherwise, I see no reason why he should be fired over it.

Personally I've better against the teams that are my favorite/root for before. I'd consider myself pretty fickle when it comes to choosing teams after all. Not that I don't avidly support them when I do, heck I go all out whenever I need to. But if I feel that they don't deserve my support anymore, I move on, simple as that.