Originally Posted by Gray Ghost
From an in-character perspective, we have a character that knows far more than most people in the setting about the tadpoles presenting a definite way to get rid of them. It's not even like she's vague about the method, she describes a process of removal and and I didn't encounter any reason to suspect she was lying at all in my playthrough. So from an in-character perspective, her solution is as close to a guarantee as we get.
Just started another playthrough (hopefully not going to finish it due to patch4 arriving :P) - THERE ABSOLUTELY IS a reason not to trust Lae'zel: In the conversation after her interrogation of Zorru, you can peer into her thoughts ([WISDOM]) and it becomes clear she is hiding something regarding the purification, so, yeah...

My guess it's going to be something like: "They are going to perform the purification on me (maybe), but you slaves are going to be fed to the dragons."

Buy it might be something else regarding the purification.