HeyDuel: Anonymously vote on your Facebook friends

Whoa. This is allowed by the facebook TOS? Including the bit at the bottom where anyone can see who has been duelled against whom, and who won?

While I'm just speculating since this doesn't seem like the type of thing I really want to give my Facebook credentials to, it seems that it wouldn't be especially anonymous if the people who are 'dueling' don't have a lot of mutual friends with each other.