Because it would filter out anyway. Look at this thread as evidence of that. It draws a line under it. He's signed his contract meaning if he does get injured it doesn't hamper his move either. Its one where either way people old have the opposing view of how it should be handled
Give over man. Most knew he'd be off in the summer, but theres no reason to come out with it now. Just look at the drama it has caused. Watson won't get a good reception by a lot of fans and there'll be those who think he shouldnt be selected to play at all in case he's just plodding along, knowing that he's off anyway.
They'll be a shit load of players at clubs knowing they'll be playing for another club next season, but that news won't be made official until the summer. Its just another classic blunder by the board to release this now when there's no benefit whatsoever.