I'm sure the Worthing fans and board aren't happy that he's moving on, but unless you are one of the very elite managers in the world, you usually don't get to pick and choose the timing of your job opportunities.
Not sure I understand the "strange timing" comments; if Adam is ready to move on in his career and feels York offer a decent opportunity, he can't exactly say to York "I'm interested but come back to me in the summer", can he.