It was looked at for a possible red card, then deemed for it to not be warranted. Without a red card being given, they were unable to correct the decision, because it wasn't in the box and couldn't be given as a pen. They could have theoretically argued that it may have led to a goal scoring opportunity. But that's not specifically part of any of the 4 scenarios in which they are supposed to be allowed to intervene. That's the point.
In my view, the idea that it should have been a red card is hyperbolic. I understand that many City fans are arguing this including yourself and I can respect that, because of how pivotal of an incident it was. I get the frustration and feeling hard done. We can agree to disagree on whether it should have been a red card, I don't see it as a red card because he was on the border of the box. You are trying to argue that it wasn't borderline, that he was clearly beyond the box, and I don't agree with that interpretation but to each his own. Perhaps that's due to looking at it through slow motion and not looking at it in real-time, where it was too close to the edge of the box from the keeper to be sure he was even over the line. I can tell we're not going to agree on the point about the red card, and that's OK. We can agree to disagree about whether or not it was deserving of a red card.
But aside from that, whether you think it should have been a red or not, the point I'm making is that short of a red card, they had no other avenue to correct the situation. As a reminder :
VAR can only intervene in four specific situations where a ‘clear and obvious error’ or ‘serious missed incident’ might have occurred. These reviewable incidents are:
Goals/no goals: This includes checking for offsides, encroachment during penalties and whether the ball crossed the line.
Penalty/no penalty: This includes checking if there was contact inside the box, if it was a simulation, or if the wrong foul was given.
Direct red cards (not second yellows): This includes reviewing if the foul was serious enough for a red card, if it was mistaken identity, or if the wrong player was sent off.
Mistaken identity: This is used to check if the referee sent off the wrong player.
None of the other 3 specific situations fit that situation, since it was outside the box. It wasn't a goal/no goal, pen/no pen, or mistaken identity. So according to their own criteria, unless a red was given, they didn't presumably have the ability to correct the error, which as I pointed out only reinforces how poorly designed VAR is.
So I'm in agreement with you that VAR is utter nonsense. You calling my post "utter nonsense" is missing the point, we both agree VAR is utter nonsense on how they operate it, I'm merely explaining to you the nonsensical criteria that they are limited to and how it limits what they can do in a situation like that.
And my other point was that the limitations on what they could do there also seems to be completely lost on Dermy and Company which only reinforces how clueless everyone involved with VAR and the process is.