Perhaps....though I suppose it may not be a person...

[He did say 'whatever or whoever', he's not tied to the idea of it being a person. Or a group of people.]

Something is happening to them at any rate. I suppose one possible answer is they're simply dead, but I don't believe any bodies have been found.

[Peter isn't working with any particular information either. This is all just blind speculation, and the acceptance that El Nysa can be...fantastical.]