Well, here's the thing though: the only reason why Byoudouin isn't playing against France is because he and Duke specifically asked for the change, so it stands to reason that Byoudouin is meant to face both Germany and Switzerland/Spain/America. So if we assume both that and that no one but Ryoma is going to play more than once, there could be a reason why Byoudouin is unable to play the finals rather than unwilling.I do agree with the Oni vs Germany but Byodoin wouldn't miss a rematch with Amadeus.
Of course it's possible we'll have a repeat of the current situation against Germany, but I'm not sure there's anyone other than Duke who Byoudouin would make an appeal for.