They are talking about personal liability. The officer is sued personally, not the city, county or state.
Except as a COP, they should know the law, the constitution and the rules.
And in this case giving the Cop immunity also limits their municipalities immunity.
Fact of the matter is, if you dont know the law, the rules, or the constitution, or if you have such an ego that you cant keep your power trip in check you have no business being in any form of law enforcement. This has been the problem for too long, to many egomaniac, ignorant, and down right bad cops giving law enforcement a bad name. Throwing qualified immunity out the window would be a good start to getting rid of the bad apples.
These cops that actually get held accountable and lose their job, just go somewhere else and do it again. If you get fired for being a bad cop, you should lose your certification, so you cant be a LEO anywhere again. Same goes for a lot of jobs. Where they restrict what you can tell a new employer about an employee, when they get fired and look for a new job.
I have met some great cops, and they deserve a lot of credit, I have also met some absolute garbage human beings that are cops and somehow as bad as they are, they somehow keep their job.