For sure it's a red herring, and for sure he was drugged by Trixie, and for sure the choice to refuse the pill will influence the plot in some way later on. My problem is that if you're going to a shady place strongly suspecting some kind of wrongdoings, and you're talking in your thoughts about how you must stay focused on investigation and you're sitting in close vicinity to a shady person offering you drugs, then it's a plain idiocy to act like he did. First drink was ok, since he always had it in sight, but the 2nd one? He should order it and then leave it or just take a sip right after it was handed to him, even if she didn't drug him then, although I had the same theory as you it's just a common sense imo.
But maybe it's just me, since I know some people that take drugs (recreational) and I never drink or eat anything with them if I'm not 200% sure it's ok to do so and even then I prefer to avoid eating and drinking, not that they ever tried anything (just tried to talk me into it on more than one occasion), but I really hate that stuff and wouldn't take any risk. Plus from a simple me-as-a-player pov I just hate when my MCs are forced to have sex with anyone and if they're acting too different than I would. With this update I've lost any connection I had with MC so it's pointless for me to continue no matter the overall story.
