[Excuse you, what? Kitty believes in science. (She also believes in magic, but she's seen that.) If homeopathic remedies worked they'd be called medicine. And spiking someone's food without their knowledge or consent? It probably shouldn't be the assassin in the conversation who knows how wrong that is.
She holds her tongue for a few reasons. One, because she doesn't want saying something to translate into Chuck doing it herself instead of giving her the the stuff to throw away. Two, because whatever remedy it was would probably do nothing instead of having an adverse effect as long as the quantity is small. Three, because she's not ready to blow up the peace they managed to get to. Four, because maybe somehow these things do work and make sense in whatever world Chuck is from in the same way that the Elric brothers actually could use "alchemy" to create things. And finally, because she doesn't want them to get crushed by a mistletoe robot.
There is a concerned look before she nods though.] Yeah, getting smashed wasn't on my to do list.