The problem is that this probably violates Facebook's TOS. Enabling a TOS violation for users as a business model would make for a pretty easy tortious interference lawsuit by Facebook against Power.
Edit: From Section 4(8) of the Facebook TOS [1]:
"You will not share your password (or in the case of developers, your secret key), let anyone else access your account, or do anything else that might jeopardize the security of your account."
It's impossible for something like Facebook to use a whitelist model for determining what you use to interact with their service, and they can't retroactively add things to their blacklist. They usually have to rely on generic rules about causing harm to the service, but then it's no longer a pure whim.
A lot of software licenses have a clause that basically allows the licensor to revoke the license on a whim.