A user has been suggesting edits that only change the pronouns. Most of them have been rejected, but some have been approved. Is this acceptable?
If you are asking if it is acceptable/right to reject such edits then the answer is "Yes".
What is particularly egregious is that he often changes quotes, thereby making them incorrect! He deliberately causes harm.
In general, I think people's pronouns should be respected regardless of gender. Ed Dean (@EDT), one of the early stalwarts of the forum always used female pronouns. That was Ed's choice and should be respected. Changing them, even in the context of other edits, would be very wrong.
Exactly the same thing applies when one of our female contributors uses female pronouns. Leave them alone.
Because we are not sexist and respect everybody's pronouns the same should apply to those who choose to use male pronouns. Changing the pronouns people use is exclusionary and we should not be doing it and not condoning it.
If I've made a spelling error in my post, or a grammatical error such as forgetting to capitalise a sentence, that's fine to correct with an edit.
If I've made a factual error in my post, it should be fixed with an edit if it doesn't change the answer I've given. E.g., "docker was first released in 2008" could easily be changed to 2013, "docker was first released in 2008, making it older than Go" could not. In the case of the latter, a downvote and a comment explaining where I'm wrong such that I can reassess my answer is best.
If I've used a pronoun you'd prefer I didn't, that is neither a spelling error, nor a factual error. It's me not catering to your wants, about which I may or may not be aware. In this situation, my mistake should be pointed out as a comment, but no downvote left, as the answer is not made incorrect by the wrong pronoun use. At that point, I can read the correction, and decide whether to honour it or not, as using pronouns is a choice. Whether I decide to or not is within my power as the author, and shouldn't be edited over.