No, that's not true. But only because the illegal sub was at bat with only 2 runners on base. lol.
Plays made by an illegal sub stand under OBR. The original player is out of the game (that is, the substitution affects him) and the illegal sub is removed, so another player must now enter. (And that legal player can be the original player if the league / tournament has reentry -- which isnt covered of course in pure obr). No player, no game.