See, this is where it gets confusing. The jam host also said this, and I quote: "All entrants in the team must be US residents. If a team is selected as a winner, they will have to sign an affidavit and tax documentation, which is why the contest is for US residents only."
To quote Coolmath Games in this thread : "To win the prizes for the game jam, developers must be a US-residents. However, non US-residents are allowed to participate in the jam, but they will not be eligible to win the prize."