So, I swim over to this island and find an abandoned camp with a journal. I read the journal. It indicates some horrible, horrible monsters are on this island. So I get get all ready and charge in only to find a bunch of horkers. Well, I guess I have some Skaal blood in me because I normally let horkers be. So I used Kyne's Peace in order to take a look around. But when I did that I got a message that Lord Tusk was too powerful for Kyne's Peace. Hmm. Lord Tusk? So I go up the hill and there is this rather larger horker, but he is glowing blue just like all the other horkers. So I just walk by him and loot the chest. If that was Lord Tusk, then it seems clear that Kyne's Peace worked on him just fine, despite the message.
Interestingly, when I used detect life, all the horkers except that one showed up as blue. But that one, which I assume is Lord Tusk, showed up as a mix of red (enemy) and blue (Kyne's Peace). Not sure why he would show up as an enemy even though he never turned aggressive. Something is out of whack there.