I'm not sure if something similar has been suggested, but I think the pausing player should only see a black screen with the text "Game is paused", nothing more. Pausing is often abused when a player is about to die or is ganked: it gives the player time to react, think about the situation, check reliable gold, decide what to buy etc. Reporting should, in theory, work against this. However, this is so common that the reporting tool clearly isn't enough.

An example of this was demonstrated in Purge's last video (timestamp 11:30):