That kind of sounds like a plot hole. A nanovirus Gestalt conscience controlled via Warp magic, yet somehow capable of forming a Skynet-type sentience that is capable of feeling remorse at being enslaved? And then not being enslaved enough to prevent it from disclosing critical information undermining its master's efforts?
Well, that's just it. Voldorius stole a piece of it and used that to force it to do his will. Mostly blackmail, some warpery.