Can't do that with a release clause though - that's the point
Suarez had a release clause of "above £40m". That's why Arsenal bid £40,000,001.
But if you refuse to agree to the players registration transfer what are people going to do?
The only thing that can happen is the player can sue you (and your reputation in negotiations is tarnished).
But it takes months and months to sue someone. This clause in Contract law has never been tested in the courts so there would be loads of appeals (how long was Bosman out of the game for).