Okay, I hope I'm not driving everyone crazy...but something else:
Nicole doesn't come across to me as prey for a pedophile, but she does come across as prey for a mean girl. One very obvious reason is she is a blabber mouth. Pedophiles like to keep their victims silent - yet Nicole was showing pictures IRL, sharing pictures online to whomever, talking to friends about her online friends. If she were groomed to be a sexual-assault victim, she would be groomed to be quiet about it. (I'm not buying that DE was afraid of her talking. For one thing, if that were the case, he wouldn't have planned for weeks, but have acted swiftly.) Mean-girls, however, just have more fodder for ridicule with someone who is so open about their lives.
I'm beginning to wonder of all the "older guys" Nicole was chatting with were really NK?! I know that's crazy and I'm not tied to it, but I really think Nicole was played, taunted, and set up for humiliation and murder....but I don't see her set up for sexual assault. And, I think the desire for humiliation and murder stems from NK. (Perhaps it has some dark sexual component too, idk?)
Okay, thanks for indulging me with multiple posts on my theory. At this point, I can't make the story fit with DE as mastermind. But I'm totally willing to admit I'm wrong once we know more. But for now, it all fits with a troubled NK in charge.
JMOpinion, subject to change.