Yes, maybe Hasbro could get you if you use the structure (intellectual property) that belongs to the game of Risk--meaning, the Classic map; the exact card values; and so on. But if you change those things, then Hasbro can't get you for developing a game where you use cards, territories that give values, and so on. Hasbro doesn't own the rights to all ideas and varieties that relate to turn-based map games with card values. Just think of the Rise of Nations franchise--which was a pretty huge game at the time--and which used similar ideas to Risk. No one could touch them.
I don't know what happened to that game on FB and I can't find any info to what has transpired. However, if Hasbro was so interesting in developing Risk on FB, they would've done that ages ago. Their latest attempt was Risk 2, which was was hosted on Zone.com and Gamespy, but it was very awkward to play and very buggy. They didn't even bother to develop Diplomacy and instead sold the license (for one game to be developed) to Paradox.
I think CC should put some thought to this and do some legal research. For instance, on this site, it says that Risk is a registered trademark of Hasbro. This is incorrect and nowhere does Hasbro make this claim. Risk is not a trademark of Hasbro and in fact is not registered as a trademark at all (in USA). You can verify it here:
http://tess2.uspto.gov. I wouldn't bother to try to register it, though. They (uspto.gov) will most likely refuse it... otherwise Habro would've done it themselves. In fact, not even Diplomacy is any longer a registered trademark. It used to be, though, but it was abandoned in 2005 by a different company (not Hasbro). However, just because Risk is not a registered trademark doesn't mean you can create a game (irregardless of its genre) and name it Risk without risking legal action from Hasbro (this is speculation from my part, as I'm not an attorney); but the fact that the name is not registered probably gives them less legal empowerment--in case they would decide to take action--since their name is not trademark protected.
If I were the guy running CC, I would do some research regarding the trademark and when it is confirmed that Hasbro doesn't own the trademark, the statement should be removed. As it looks now, it sounds as if CC is excusing itself for having created a game on concepts similar to Risk. It looks like it wants to cover its ass--something it doesn't need to do.
"Risk is our business" -- Capt. James T. Kirk
Note: my post should not be taken as legal advice and I cannot be held accountable for punitive damages that may occour for following any of my statements. There... now I covered my ass. lolz :p