Moving because of his job would be fine. Hey, it happened with my family when I was a kid. As long as Maria and Alan get their goodbyes and well-wishes with Sarah Jane and company. Bonus points if there's a torch-passing scene between Maria and Rani, to ease the transition, although I doubt it will happen. Super-bonus points if Alan confesses his love for Sarah Jane to her before he goes, although I REALLY doubt it will happen.