4. The main problem I have with it is that it can cause or increase machlokes, since then someone thinks you wrote something bad about them and maybe you didn’t, or maybe it wasn’t as bad as they think, or maybe it wasn’t bad at all and is being misunderstood by the moderators.
If it were posted and the person misunderstood it, the other person would have a chance to explain, but this way they don’t, so the other person can be left thinking the first person said something bad about them when they didn’t or when it wasn’t as bad as they thought.
It can be worse sometimes to hint that someone said something bad about you without saying what it was. But obviously, if someone really thinks that something is l”h, the best is to simply delete with no (public) comment.