The unique horker named Lord Tusk respawns on Horker Island. I can't think of any reason that this was intentional. The only possible problem might be if this location can be used for a radiant quest, which I haven't ever experienced. You would probably have to replace him with a generic horker boss after the location is cleared the first time.
Actor ID: DLC2dunHorkerIslandEncHorker
Reference ID: 040264AA