I really like the guy and I respect him a lot. I'd prefer it if he finished his career as a Newcastle United player especially after being at the club for such a long time and being one of our longest serving players. I also still see him as a decent enough number 2 for us. Blind loyalty from my part if you want.
But I suppose that from his point of view, he doesn't have long left in his career, so ending it on a high (ie. being number 1 at another club) is the best thing for him to do.