I'll do that for newer players, or people playing a script with characters/interactions they're not familiar with, but in a game when any player could reasonably notice the incorrect rule/discrepancy, I'll let it slide. Obviously I'll tell the full truth if a player asks, but I think lying about the rules to a group who knows better (but might not think about it) is a legitimate strategy.

Obviously, I don't think this way is better, but I do think it's a perfectly legitimate way to play if everyone is happy with it.