IANAL, but I don't think that "too inspired" is really the sort of thing that is covered by the DMCA, and in any case, you can't file a notice to take down the whole project just because you think three icons are derived from your work.
As for the newspaper icon, it has already been pointed out that LayerVault's version is far more similar to this icon from The Noun Project (http://thenounproject.com/noun/newspaper/) than it is to the Flat UI version.
The other claims I've seen are that the gears icon (not even close), the "talking head" (not even close), and the color palette (not something you can copyright).
More importantly, this fork doesn't seem to contain any of those disputed icons, so I don't think there's anything improper here.
I did consider that they might have bought a license from TNP, but if they had, that would not grant them exclusive rights to the icon.
Let's suppose they had bought such a license, and let's call the shared similarity between the LV icon and the FUI icon "X". Let's also suppose that X is copyrightable. The problem is that X is also shared by the TNP icon. So LV wouldn't have ownership of X, and wouldn't have any right to file a DMCA notice based on it.
As for the newspaper icon, it has already been pointed out that LayerVault's version is far more similar to this icon from The Noun Project (http://thenounproject.com/noun/newspaper/) than it is to the Flat UI version.
The other claims I've seen are that the gears icon (not even close), the "talking head" (not even close), and the color palette (not something you can copyright).
More importantly, this fork doesn't seem to contain any of those disputed icons, so I don't think there's anything improper here.