I agree. I've worked at a national lab before and I immediately thought this service is a massive security risk. It will definitely be hard for some scientists to use these kind of cloud services, especially if their research truly is cutting edge and sensitive. I think many people will just ignore things like this because they want to keep their jobs, etc.
As mentioned above, there is an open-source version for those who want full control. The free cloud version is mainly for convenience and faster iteration. We don’t store manuscript files longer than necessary to generate feedback (https://www.rigorous.company/privacy), and we have no intention of using manuscripts for anything beyond testing the AI reviewer.