That's the first question I had come to mind. I did not expect it appearing in the mod queue.... The user just tagged another name under his own profile post. To make the other user aware of his own profile post.
Off the top of my head I think he seen this before and I think it relates to the content being valid, somehow, while it leaves an orphaned moderator queue record.
I think in terms of reproducing it, if you unapproved a profile post, then edited the message_state manually in the DB to be valid, it would leave the moderator queue record there and it would never be possible to alter its state there because I think we check for that before changing anything.
If my hunch is correct, the real question is how it came to be in that state. That could well be an add on but it might not be possible to reproduce it now.
Could it be that crossing over super admins, who set different states at the same time, caused the problem? Because I was switching between accounts, and I can not really remember the order of actions but, when I did different tries like inline-delete, then unapproval, then moderation queue delete and that from different accounts on different devices (smartphone and desktop), that the database got a hiccup due to wrong record states? I still wonder why it finally worked again...
Not sure how it happened. That seems unlikely unless it literally happened in the same split second.
As for why it worked, I think the moderation queue actions will only happen if the content is 'moderated'. It's possible the content was actually 'visible' despite there still being a record in the moderation queue (which is a separate table). If this was the case then going to the content and deleting it would work because it doesn't concern itself with what the current state is.
I'm still sort of guessing at the moment but it's really the only thing that makes sense.
I would say unless it happens again, don't worry about it.