Regardless of one's opinions of Thiel, most opposition to Palantir would be political rather than personal. This firm's actions have made society poorer and less free, in multiple nations.
https://slate.com/technology/2019/05/documents-reveal-palant...
https://www.theverge.com/2018/2/27/17054740/palantir-predict...
Not saying that's the case here, but one could be forgiven for assuming that a lot of 'predictive policing' stuff is snake oil, but dangerous snake oil.