The popup for reporting is good (though I have never seen it) for problem people, but from some of what I have seen, it is overused sometimes. The popup grabs someone's attention fast, and that shapes a lot of players up rather quickly. Others are a lost cause, obviously. I think perhaps there should be a middle ground between a full report and just telling someone to chill out or you will report them, which often results in becoming a target. This would cut down on reports mods have to go through.
So, my suggestion is as follows. Rather than sending a report right away, there would be an option (default) to send a warning to the player that they might get reported. A popup would appear like report, but nothing would be sent.
"Notice! You will be reported for [reason] if you do not adjust your behavior. Your actions are being recorded. A full report could result in a mute or ban."