EDIT: This was posted as a response to the original version of the question which explicitly mentioned also tag edits.
I will try to address mainly the general question about editing closed questions - as far as I can tell your question is intended to be general and not only about the edit you linked to. (We can leave comments and chat for discussion of this specific edit. But certainly the reason that I was the editor in question was a contributing factor why I decided to post an answer. So I briefly touch also this specific edit in this answer - but that is not the main point of the answer.)