Its a guess by the ref, you can tell by his body language and also by the way he is not alert enough to the handbags flare up which followed, did he even caution the gk? Had he been certain of his decision I think he would have ? I don't even think he took any cautions for the melee, in his head am guessing (and only a guess of course) that he was not wanting to compound his own dodgy call by putting folk into the book aswell, Am still going YC to City player and no pen, but, if someone else is giving the pen here, that's understandable too. Bottom line is, that referee was not able to make a call, as he had remained static even though ball was fired into the danger area,, he neither got wide to give himself an angle, or close enough to sell his call. I think that's the lesson I take from this clip more than the actual decision itself.