A lot of so-called "libre" software is awful, and explicitly harmful to one's freedom and health (eg web browsers such as firefox), they are too complex for anyone to properly audit (again, firefox, systemd, X11), even if they have no explicit backdoors, they probably have hundreds of exploitable bugs all over the place and the three-letter-ag's know about them. A lot of proprietary software, on the other hand, may be comparatively innocuous, it is already restricted by the os, and can be further virtualized.
I would of course prefer open-source programs everywhere, but the wuole distinction between "leebray" and otherwise is an artificial one and strictly living by it is being an ideologue. Moreover, the term "free software" excludes many ooen source projects simply because they have a different (more permissive, it turns out) license.
I don't have time to audit every software that I compile or that I get as binary from my distribution's package manager. Even if I did read the code, I wouldn't be able to pay enough attention to spot malicious code or dangerous bugs.