Yep, I would also made the cunt or her master drink the tea and stop them from drinking/swallowing anything else.
If it's just tea then you would just have bad aftertaste since it wouldn't be one made how you like it. But if it's poisoned then you either start dying or try to take antidote which both show how right she was. And if they were a little smarter then they would have taken antidote earlier and then drank the poisoned tea - this way you completely fuck up with MC because you "prove" that she was wrong.
But of course that would take a strong will from FeMC to force them to drink it and we know how broken she still is.
But the strangest thing is how the whole situation happens without MC, Mage and his servant. Like the very next panel that the old healer leaves we are shown FeMC group like nothing happened. And they literally just got the tea from the cunt student.
Could have been really cool scene if it happened or if what
@comeonnow0 said happened.
What we got was comically obvious.