The judge is the GM. The trigger is a report from another player. Just like every other single report, the other player also needs compelling evidence that there is a deliberate breach of the ToS.
It has already been established that when someone genuinely disconnects, they have to wait for the server to recognise they've been logged out and then join a queue. I suspect people who use this exploit are bypassing the server delay.
As such, people who genuinely disconnect during these dungeons generally wait til people finish the cutscene anyway because there really isn't a time advantage in going alone.