Security and open source philosophy are two completely orthogonal problems. You can a have an open source system that is the most secure, sandboxed implementation there is. Likewise you can have a completely insecure closed source proprietary system.
The freedom in open source could be the freedom to structure your system in the most secure way possible for running untrusted applications. It’s just that no one managed to achieve this yet in a satisfying way.
Not entirely. A few months ago I was reading about a controversy where the Emacs dev team was concerned about the ethics of conducting an online survey. Can you believe that? That's why I like using their software. You just know people who are that extreme philosophically will never in a million years betray you.
Don't you think tools like Bochs, QEMU, gVisor, etc. are reasonably satisfying? Security is a hard problem since there's an endless push and shove around its tradeoffs hence why sometimes the best one can afford is monitoring.
The freedom in open source could be the freedom to structure your system in the most secure way possible for running untrusted applications. It’s just that no one managed to achieve this yet in a satisfying way.