The government can receive money from this guy with no added costs, as it is unlikely that Thiel poses a threat to NZ or its citizens. Even if he builds a mansion or something that's still a net positive that would be irresponsible not to take advantage of. (assuming the funds are not lost to corruption)

Can granting Thiel citizenship create problems in the future, in terms of kickstarting negative trends? That's a possibility but it seems like a nebulous and remote one.