Well maybe i'm a little biased being a man utd fan but personally i think he's been a great captain for utd this season. Yeah he can be a bit goofy, but he's always yelling out commands around the team always aware of whats going on on the pitch. Plus he doesn't get in a big strop at the referee if a decision doesn't go his way *cough* john terry *cough*
It's only temporary anyway. Capello is rotating the arm band around in these friendly games, he isn't naming a permanent captain until the world cup so no reason why he doesn't deserve a chance at it.