You can’t enslave a free man.
Only person can do that to a man is himself.
No, sir—you can’t enslave a free man.
The most you can do is kill him.
Free Men by Robert A. Heinlein (Short Story)
I love Robert Heinlein’s writing and have every one of his books, including the one with the short story you cite. Wonder what he would say about all this if he were still alive? He probably would not be too surprised.