Dude,he's not plumbing it back in...
He has one, working, vent to atmosphere BOV hidden under his front bar to make noise for his own personal enjoyment, or whatever reason he wants...
He has another non-working, aka 'dummy' BOV, which looks standard and is mounted in the standard position, which he hopes to fool police if in the event he gets pulled over...
i don't think police are gonna fall for it personally, but hey at least he's being creative...