Yes, I read that. I think she probably died of natural causes. One of the people around her said that she was ok but upset and then she suddenly sank and was just gone.
I think the group as a whole wasn’t very worried because they had their life jackets on, they were all accounted for (although I believe she had been pulled out of the plane by Yamamoto and the pilot) and they knew they’d be rescued because the pilot had called. But she was evidently not very fit or accustomed to being in water, and I think she just freaked out and died.
If it was sabotage, I’m not sure she would have been the target, in any case. Perhaps they all were.
I suppose it's neither here nor there, but I would like to say she didn't sink, she was wearing a life-preserver jacket which kept her head out of the water.