Its a godforsaken hacked car man, its not just a RBX1 @ 1551HP.
How can you say he can play the game however he wants in reference to the civics.
Well, simply, it's an old argument, but it's his game, who are we to tell him what he can and can't do with it? Of course, you can advise against it, but someone can send him a copy of the car and there is absolutely nothing you can do about it. Why are you so bothered about what other people do with their games? If you don't want them in your drag lobbies, there's a power limit that can be imposed, or alternatively, if you don't want to race them, just move out of the way when one lines up to drag?
Of course, if we're talking about hacking in general, I'm against that, since the day will come when someone will inevitably shove a more manageable amount of power into something which can actually use it (say 1500hp in a R35), and that will be absolute hell for online racing in general. But with the Civic and its ridiculous inability to get its power down, I'd treat it as a laugh, a novelty. It does no real harm to anyone and can easily be removed from the track with a simple power restriction in the rooms (most "good" drag rooms have a power limit imposed already to block X1s, so if we're talking drag rooms, no real worries there).
As for the legal side of things, I'll stick with the argument that, if PD really didn't want these cars around, they'd have taken the chance to get rid of them with a patch, wouldn't they? And if they do do something about it and we get tangled up with the law, well…we can't say we didn't see it coming, did we?
TL;DR- It's wrong, but it is very much up to the individual to decide and take responsibility of their actions. They ask for it, they get it, but should know what it could result in if PD do act.
My opinion on this matter, anyways.