yes i know that but the emporer as same abiltiy but stronger that why he master death
Uhh, come again?
Nihilus has that feat as part of being a Wound. Vitiate has created a technique/ritual that does almost the same thing, without having it turning yourself into a Force dark hole. Logically, and correct me if I'm wrong, this would mean that such an attack would do nothing on Nihilus.
How can you drink from a cup thats already empty? Nihilus has no Force of his own, and merely uses that of his followers/ slaves to channel the Force through them, to himself.