Watch it again
@newyddion , the refis pushed before the red card, the intimidation comes after. Admittedly the manager's sending off on the TV footage looks soft, buts that's before you realise we have only seen a little bit of his Yosemite Sam impersonation as he is shooting off at the Fourth official which we don't see and there is probably more mouthing off at the ref.
William himself goes all puppy dog eyed and points at his chest where his by now comatose hand is resting, he is doing his best to deceive the ref, maybe Mitrovic believed him and felt a massive injustice with it, but in reality the ref made the right call at every point.