Considering his other values, the question here might be if he couldn't fire people for reasons the rest of the corporation considers normal - like taking time off, not working on weekends or similar.
For someone trying to do that, it might look like its "impossible for fire someone".
It's how it works at most big companies. There's a very big impact to morale if people think they'll get sacked at the end of a big project or if VP's best friend needs a job. The normal way to onboard a new better person is to open up a new position, like repurposing an open headcount from somewhere else, and then shift responsibilities between the new person and old person.
It's certainly a lot harder to fire people than at a startup. You need multiple review cycles with poor ratings, a Performance Improvement Plan, more review cycles of bad ratings, etc. But most people don't want to hang on through that, so they leave since it just sucks to be on a team where you are not valued. But you can definitely hang on for 18 months pretty easily with everyone unhappy with your work if you want to.
So it's not really the same as government jobs where you really can't be fired, but it's very different from a startup where everything can be going fine, you lose a big customer and a week later 10% of the company is gone to keep the burn rate low.
I found this surprising. I thought this was primarily a problem in union / government positions.