Nobody in the rest of the world cares that he's American. Pro cyclists ride for their team, not their country.

It sounds pretty fishy though that he tested positive on only one stage (the one after he bonked). It's probably simply a case of his body reacting to the drain on his system from the previous stage. Jacking testosterone levels artificially on race day serves little purpose because testosterone isn't ergogenic, it's anabolic. Athletes use it during their training phases, not typically during competition.