> IANAL; have you looked down any legal avenues?

I'd have thought it went something like "Facebook's servers; Facebook's rules". They don't have to allow any content they don't want, and if they had a spam coming from an URL they're probably going to block that.

It's unfortunate that a company's customer got that whole company banned from Facebook. It could be a lot worse - all those networks could share data about who they've banned and the company could be banned across Twitter and etc as well.