I don't see the bunkers as being as useful as some might imagine them to be. In the kind of apocalyptic scenario which would actually make him want to move to the bunker in New Zealand, why would his security people bother to keep taking orders from him instead of just taking his stuff and demoting him to an advisor or maybe even killing him? I guess it's better than dying outside the bunkers, but there's a good chance that he would lose his status and live subordinate to whoever the local warlord turns out to be.