Principle doesn't come into it. If we are contractually obliged to pay him his loyalty bonus we have to pay it.
Appreciate context you make, but basis of loyalty is having not asked for transfer, these days things have moved way past transfer requests, I would say advising he won't ever play again and wants to move to Madrid morally mean he is asking for a move.
However, you are right legally if he hasnt actually submitted a request then he is probably due. Easy answer is to advise him we don't want to sell him, but will if he asks formally.
He needs to stop being such a greedy bastard.