The owner's comment is eye-catching but I'm not sure how relevant it is. He wasn't out there with them. I read the last two articles linked and they indicate Stewart gave the ok sign twice and that he and the boat were drifting apart, necessitating a repositioning of the boat. Assuming that's accurate, I don't know that jumping in would've done much good; may not have been close enough to reach him. And that kind of underscores a point that has probably been a made a million times before - we weren't there and don't know exactly what happened. Likely just an unfortunate combination of bad dive practice and dealing with a medical issue on the boat; bad things happen when you dive aggressively.