No? Your link says nothing about "completely," you just made that up. What it does say is that they remove the "nonessential" bits, plus flip the HAP bit. You can do both of these things yourself with me_cleaner, but it's not good enough. Exploitable vulnerabilities have been found in the bits that cannot be removed.

edit: E.g. https://nitter.dark.fail/rootkovska/status/93845887552266649...

Not completely, but to a large extent: https://puri.sm/learn/software-freedom-in-perspective/