I realize I'm posting too late to ever get read, but this another arguement into my head:
If I duplicate Facebook's site and change only the breast policy, do you think that people will switch, even though the new one is better?
If you were to duplicate Facebook's site, you'd be immediately sued into oblivion. IIRC, I've seen a few stories about Facebook's patents get posted over the last couple years. Then there are the trademark and copyright concerns.
In effect, Facebook has a government protected monopoly. As such, they are obligated to open and accessable. If they decide to ban a (protected) class of people based on private proptery rights, they should be obligated to return the public property they have in the forms of patents, trademarks, and copyrights.