grenv: If my question wasn't, your answer was very clear :-)
Making moves that leave the king in check illegal is indeed an alternative formulation in my personal ruleset ( http://www.pion.ch/echecs/variante.php?jeu=ambigus&rubrique=regles&changer_langue=E ) . Basically it doesn't change the game at all (except for the stalemate, but I like the fact that stalemate is a win), has the advantage to cut off silly mistakes, to make the game more chess-like, but the disadvantages to make the rules more difficult to understand, three times as long and more difficult to implement.
The last reason is enough to make any programer prefer the simple no-check no-mate formulation, and even if I supported your proposition, I am sure that Fencer would not. He didn't implement checks in either Atomic Chess or Extinction Chess, and rightly so imho.