Two things here make no sense to me.
Arsenal can’t just sell to the highest bidder as it is down to the player where he goes. The rags could offer the moon and stars to Arsenal and it would make no difference if he doesn’t want to go there.
At 29yo he’s got one real chance left for trophy winning. Why would he squander that chance by swapping a club which may win the occasional FA cup for another club which may win err..the occasional FA cup. The north London arsenal for the Manchester version.
Two years down the line he finds himself in the same boat he’s in now, only he’s two years older.