Ah. Mutant because of mutated genes as opposed to having an actual X-gene. Which would make him a mutate not necessarily a mutant But...Enh!
But like I said...Mutant or not he was never a significant part of X-lore except in the most tangential stories to warrant my interest in the debate. Even the recent stupid Krakoan LS more or less proved why it's an irrelevant topic.