This appears to still be happening to vampires in NPC mode. One of my sims Ana and her spellcaster celebrity boyfriend Daud had what looked like a date at the restaurant my current sim is running, and Ana kept getting up every few seconds to drink a plasma pack. She also wouldn't eat her garden salad, unlike other vampire guests who come in occasionally (they all have the weak stomach trait), and those ones happily eat and barf and eat and barf ad nauseum... pun intended. Anyways, while Ana's salad sat on the table, it screwed up the restaurant AI and no further food would be presented to the couple until I had my sim clean up the salad. That table never fully fixed itself by the time I gave up and shut down the restaurant at around 5am (15 hour shift anyone?) because the couple's date appeared to be stuck doing not much but conversing while the girl guzzled plasma packs. What's weird is I play a lot of vampires, including my SuperSim Tirsden, and I'm pretty sure I've never seen any of them autonomously drink a plasma pack whether in active play or NPC mode.
TL;DR: Restaurants do indeed seem to make some vampires chug plasma packs and today is the first time I noticed it.
