If one person on the team is a US resident though, could they themselves receive the prize money on behalf of the team? I don't see why this would be a problem
Having global prizes is a standard set by most game jams originating from the US. GameName, ThatGameJam, I could go on. If they aren't even willing to let a US origin resident distribute the prize to the rest of the team, surely it is normal to think they might have some ulterior motive in play with such a restriction, considering the burden falls on the receiving participant...