That offside analogy isn't very helpful. It's more like getting a second yellow, because you kicked the ball towards the goal, a couple of centiseconds after the offside whistle.
And while we are correcting analogies - the bus driver one wasn't very good either, because of the huge chasm in relative frequency. Rather than driving daily, this would be much more akin to driving a bus full of tourists to (say Greece), making a 15 minute cigarette break, and then deciding that the guy who is late from the toilet and running towards you, deserves to have the door slammed shut before his face, because - hey, rules are rules after all, and you did say 15 minutes.
None of this is as relevant as the fact that we simply would not know that this ever happened, had they just registered him. The whole precedent setting argument is therefore ludicrous.