> but I'd much rather data be in the hands of a corporation that doesn't leak it

So would I and I think Palantir will leak it.

Is there any proof that Palantir has ever leaked client data? From a security perspective they are one of the few companies that hold IL6, which means they can handle highly classified/top secret information.

They work with many international governments and companies, and I would imagine any sort of unapproved leak would be disastrous for their brand.