I started a Grom ME campaign just to check and it looks like the Black Orc Boss is available to me. I heard on another forum someone speculating that it only shows up if you’ve won a campaign with Grimgor since the Warden+Paunch DLC dropped. Which I have, but I can’t imagine a ton of people have done so since the new shiny lord (Grom) is probably far more popular right now. No idea if that speculation is correct or not, just passing along rumour du jour.