Then he offers you the Astral tadpole which isn't being forced upon you, instead your illithid parts of your own body are craving for it due to its power. If you consume tadpoles, your tadpole is once again craving for power and you need to pass yet another Wisdom check. So this is in fact your fault for accepting to consume them in the first place knowing their effects, because you wanted to get strong. Why is it now an issue suddenly that you're being offered more power? Because of the yucky face?
If you did not trust the Dream Guardian and did not consume tadpoles, you can throw the Astral Tadpole to the ground and stop on it. If you did trust the Guardian enough to consume even just one of them, you will have to resist the tadpole's cry in order to not partially transform. Failing the skill check you will partially transform against your will. The party does not want to transform, so advising them to take steps that facilitate an undesired transformation is betrayal.
It's not just "yucky face" it's a partial transformation into something you do not want to be. Besides this, it's also a try once situation. If you tried one, then decide you didn't like it, you are still trapped. It's not the drug dealer's fault that someone becomes an addict, hm?
We are not the Emperor's friends or allies, we are its tools. That's ok by me, but it also means that it is nothing but a tool for the group to be discarded when it stops serving our interests. I am not any more grateful to it than to Viconia.
