As with all decisions to deliver a "cheap shot", the decision is made by the player. When it's delivered after time has expired, the game is over and the consequences of that decision still matter, and should be applied. The contest, is however, over and the consequences should be delivered by the appropriate authority, likely some governing body responsible for the contest, ans should absolutely be reported to that governing body for whatever discinplinary action THEY decide, to serve as an instructional lesson to the guilty player.