@Klumpen Hm-kay, obviously I dismissed it to quickly.
Let's see, it also is a coating, but while simpler applied - according to what you quoted - it requires complex post processing. Since
@comradekingu asked for it being used as an additive to the plastic for the case, we are still not provided with a way to do that.
My guess for now would be, to have the density required we'd need to add that much of it, that the case would lose its structural integrity. And then (after the mold injection) we'd have no way to do the complex post processing. But as I said just a guess.
Additionally it might be that those short nanotubes used in the spray need to be held in some kind of liquid carrier substance, which might make it inappropriate as an additive. I do not know about that - just a consideration.
[doublepost=1463330575,1463326445][/doublepost]Furthermore even if some form of Vantablack could be used as an additive and light entering the case material would be mostly absorb, I'd expect the case's surface to still have a significant (by comparison) amount of shinyness - matte or glossy depending on the finish. Could be a good looking design by itself, though.