Not true they can be fired!
I personally know of several cases.
The problem is it very hard. A supervisor must be determined to do it, be persistent & must document their ass off! Needless to say it’s very hard, most supervisors don’t want to take the time or trouble. If the problem can be solved by moving the employee elsewhere that’s what is done. Path of least resistance!
The problem with this guy is what are you firing him for? His political beliefs? Just being a commie isn’t a termination offense any more. It hasn’t been since the 1970s. Those people used to be weeded out to some extent by loyalty oaths. You’d have to catch him in the act of sabotaging policy & have documented 9 ways to Sunday! Him just flapping his gums & sounding like a macho revolutionary isn’t enough! In the 1991 Gulf War there was a Treasury employee with a clearance (or so I was told regarding the clearance!) who went Iraq with those other peace-niks to stand with Saddam and be voluntary hostages (Quakers I think!). I Sm pretty sure he got his job back.
THE POTUS...should BE ABLE TO FIRE ANYONE!!!
I know of a state employee that has decades of firing worthy escapades including one that should have had him in jail.
He still has his cushy easy state job.