You also thought "vampire being mind controlled" was a different kind of vampire, so...:P
It mostly just means that Malack was nothing more than a custom-made EEEEEEEEEEEEVIL CREATURE who didn't become evil so much as never really make an independent choice in his entire undeath. That takes away some of the impact from the character; it means that he really WAS nothing more than a minion following orders, rather than an independent being who became monstrous through his own choices.
Those tend to feel more monstrous to me. Still, it's Rich's story and Rich's characters, and that I wouldn't have written it that way means less than nothing.