If that's indeed them who sent the notice, they are just shitting all over their reputation and alienating a lot of people. Talk about "starting off on the wrong foot"... and for what? A design that is border-line trivial. It would seem that their best option for getting the situation under control is to release their own version of the toolkit. A version that is sufficiently different from their original background-color, border-radius and icon @font-face. If not, they are bound to repeat the clone wars of Svbtle.
Edit | LayerVault actually appears to be a pretty useful product, clearly with a lot of thought sunk into it. Which makes it twice as unfortunate that they decided to pursue something like this. Google "LayerVault videos" if interested.