"It sounds (to me) like Moe and Taz brought Bridget and KEG back to the hotel with them. I'm curious why HKS chose to meet them all in the lobby and then go with them back to the room where (it appears) he and KEG left from to go to the boat."
Just another theory.....
It's all in the matter of timing. HKS doesn't know exactly how long it will take for the lethal dose to take effect.
HKS doses ANS, thinking that Moe/Taz/Brig/KEG will be arriving soon to the room and then he and KEG will go to the boat broker deal. But, the arrival of Moe/Taz/Brig/KEG is delayed and HKS panics because he realizes he's going to be the last one to be with ANS alive... not good. In his panic, he decides he'll leave the scene, but when he's met in the lobby by Moe/Taz/Brig/KEG HKS accompanies them back up to the suite. Why? He's got to run interference (keep them away from ANS's room, suggest they not disturb her, etc.). Wouldn't look too good if they all walked in and found ANS dead (if indeed she has died at this point) but he doesn't know if she's died yet, he's just buying time in order to make his get-away.
Then, he and KEG leave for the boat broker deal. That way, he's not present when she's discovered dead, thinking that the finger will be pointed at those present in the suite vs. him.
That's a very very good theory. I likes.
Wouldn't you think Brig/KEG had their own suite? And maybe (just maybe) the suite that they went back to was actually that suite? Someone did say that Mo and Taz went into their room (probably was Mo that said that), but he didn't say that the others weren't at another suite. Did he ever specifically say that everyone returned to Anna's suite?
It's just a question.