True that Federal employees can't be fired but there are numerous ways around that problem.
Transfer them.
Put them in jobs they are going to hate.
Create new positions OVER them.
Institute another hierarchy such as ADM Jacoby did at DIA when he couldn't get rid of the entrenched "old guard" there.
WE could also do our part and elect Congress Critters who projmise to halve Gommit by half. If there were a 50% reduction in the Government, these yodels would be either forcibly retired, or working in Alaska or some equivalently wonderful place. /sarc
For many years, the Department of the Interior was the dumping ground for worthless federal employees. Then, under Jimmah Cahtah, they got real power over the coal industry. I remember a couple of fart-brain GS-15s who came around the place I worked. They were laughable but they could put you out of business.
On the other hand, none of that applies to CIA employees. They can be fired at will for any reason. Sometimes they've even shown up dead.