To take it to an extreme, if you are a manager on relatively low income in league 1 and you hate Arsenal, but they come in with offer of job, double money etc etc, any petty reason to dislike them will go in an instant.
I know we are not Arsenal but you get my point - huge step up in money, potential and profile (but also pressure).
If he doesn't want it I think it would be due to the pressure early in his career.