In my opinion, if someone edits a post before matches have started, they should get a warning for a first time offense, and some sort of small suspension after - a disqualification for the current tournament, and maybe a suspension for one or two tournaments after.
If someone deletes a post after their pick has lost and then posts a new one like Hantu, a three month suspension off the bat is appropriate, and a permamanent ban is sufficient for a repeat offense.