Facebook has been doing a crackdown on a lot of this. Esp. for phishing reasons. I know they are blocking co.cc as well.
I'm honestly not sure even Administration asking would do anything. It's a safety risk for the users of facebook (imagine Mark saying that.. haha. When did he start caring about safety?) But it still is. Many urls, especially subdomains of sites that don't even technically exist (like x10.bz, x10.mx, etc) are being blocked by facebook, and it's ultimately failed. Because as mentioned in this thread, people can use a link-shortening service to shorten their link (bad or not), and post it wherever they want.