As far as I understand it, the extradition is because a criminal offense has been alleged ie that he caused actual damage ($500? per hack?) to systems in the USA!

I think it unfair if the same level of proof is not needed for extradition eather way round. US has a history of forcing others to their way of thinking. It is expected that the hacker (if proved guilty)will face a lengthy jail term, whereas despite the UK coroners court demanding attendance of US servicemen to ascertain how some UK soldiers were killed they were shielded by the US!
The level of guilt was apparent to most due to cockpit communications between the two combat aircraft and their base being recorded!
It can't be just me that sees this disparity!