I used to be a member at JFX before joining here. It was run by Arnold Cousart, a good friend of Adnan's.
I don't believe Adnan was a plant. I believe he started out to take advantage of her, but then as he got to know her he started to care about her as a person. I also believe he was suckered into helping Lynne at a certain point, just prior to her hospitalizations, with the understanding that he was helping Britney.
Example: I think he did this interview with ET at the request of Lynne and Lou.
He also assisted in the filming of FTR. I believe Jamie allowed them to reunite for a short time period - just long enough to get FTR filmed. And then Adnan was booted back out of the circle again.
I'm sure Adnan has signed an NDA, and I'm positive Jamie (or Britney's security) have physically threatened him in the past...but I have no idea why nobody is reaching out to him.
He's seen more than almost anybody, and has quite a story to tell.