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How to deal with reactor if the reactor is no more or he thinks the post is still bad?

I was thinking of the reaction system for a long time. A question had came to my mind :

> If an answer is poorly written (or outdated) and a person had reacted to that as Outdated. Later, when the author of that answer edit that post and remove all those outdated content and newly write new "things" than the reactor must retract his reaction. But what should we do if the reactor is no more or he is no more in the community? What if the reactor is right there but he don't want to retract that? And, if the reactor thinks that the post is not helpful but everyone on the community thinks that's helpful than he obviously won't retract. So can moderator retract that reaction? Like as, a beginner programmer can't understand what does seniors say cause they may think it is not understandable for him so it's unhelpful (I am assuming that the reactor's idea isn't good but he will react that post as unhelpful).

I know it would be better if I had separated the question but I don't have any idea, what mod can do with reaction since I haven't cloned the updated the new version of QPixel.