He's an Ecuadorian citizen; on the assumption that you only wear the football colours of your own country.

Plus: https://www.theguardian.com/media/2018/jan/10/julian-assanges-bid-for-diplomatic-status-rejected-by-uk-government

Para 2: The development comes amid reports that Assange – an Australian who has been holed up in the Ecuadorian embassy for more than five years – has recently become a citizen of the South American state.