The problem is that, while the ref and pretty much everyone else watching knew with some confidence that he wasn't injured, nobody could be 100% sure until the physios came on. He decided he wasn't going to allow them on until he had carded Dzeko and then Dzeko decided he wasn't going to move till they came on so that he could save face.
Unless he's 100% sure he isn't injured (which he can't really be), it was the wrong path to take. It just ended up being a ridiculous staring contest which Probert would always lose.