Just to be sure, what exactly is the problem with the carrier? It it the presence of the aircraft carrier (In which case, we're in the Nexus, it just pulled one in from somewhere), the massive threat that it poses (Can't really argue that), or the idea of the police/enforcers having a fighting chance against some of the stronger supernaturals that aren't explicitly immune to military weaponry?
All three, frankly. To the first, even if a carrier could just show up in the Nexus out of nowhere, it would be useless, because no-one knows how to actually
use it, and there's no reason the government would find it in any case. To the second, yes, that is the biggest issue, because the whole reason the government is the government is precisely
because it possesses overwhelming force relative to ordinary citizens (support from the populace also helps somewhat, but it seems unlikely that the average person in the Nexus would be opposed to a government that could help keep the supernatural creatures in check).
To the third, also yes, because the whole point of the setting is that the government
can't do very much about the supernatural threat and, indeed, lacks much power at all. There's nothing wrong with giving enforcers the chance to be a threat to supernatural entities, but they can't be enough of a threat to negate the ability of heroic characters to actually make a real difference. And, having an aircraft carrier goes beyond just giving them a "fighting chance", it makes it pretty much impossible to avoid them. Even if you're immune to normal weapons, they can still make your life absolute hell by blowing stuff up.
