I'm glad you mentioned this, I always thought they excluded him way too early. He was the last person to see her, and I do not think that this was the driver PAK's first situation where a girl has gotten out of control. I feel like Pak just wanted to get out of the area, but I also think that he was more involved in the logistical planning, and ultimately what happened to Shannan and the rest of the girls. Sure she was freaking out and drugs make you hallucinate, but why would she freak out around these folks if she knew them? Especially her driver. I think Shannan was probably used to "work place hazards" but whatever took place freaked her out so much that she ran into open marsh and got lost. intoxicated or not, that's fight or flight trying to get you out of a dangerous situation.
Another thing, sidenote, since losing Shannan the Gilbert family has somewhat fallen apart. Shannan's sister( mh issues) murdered their mom, and there's only one of Shannan's sisters, and her father taking care of shannan and her sister's kids. Her sister is doing 25 to life in Ulster county Prison. It's a real shame. I really hope they can figure this out to get the family some answers.