He hasn't refused, he is fighting extradition in court. How can he have refused to submit to justice if he is taking part in court proceedings? Submitting to justice is not the same as doing whatever you are told, at least not since the establishment of habeas corpus as a standard.
Correct me if I'm wrong, but the funds are frozen by the US, not NZ. "Submitting to Justice" does not mean "Submit to Prosecutor." It means making yourself available to the Court for the purpose of defending yourself at risk of being found guilty and punished.
US Courts are not going to consider the petitions of someone who won't show up to Court. For example, Roman Polanski wishes to petition the US Courts regarding his Criminal Case. The US Courts correctly refuse to hear those petitions so long as Polanski is hiding from the Court.
The funds are seized and frozen by Hong Kong and New Zealand at the request of the US authorities, which is how he has already managed to get some of it back from the New Zealand authorites.