Compared to Thiel Thunberg is the voice of reason. Actually, she is the voice of reason compared to a lot of wealthy and powerful people. And that's why they're scared shitless of her: you can't really argue with someone who has nothing to lose and speaks truth to power like that.
Thunberg has issues, sure. She's pretty open about them too. But that has zero bearing on her various positions and they are as solid as they are ethically clean. As always, there are people that would love to 'shoot the messenger' and in many cases this appears as a rather literal proposition. So far it hasn't happened but I'm afraid that one of these days it will. We need her. Far, far more than we need Thiel.