Police probably shouldn't be sued for performing their duties. But the issue is that with a few choice words (I feared for my safety/life) their "duties" cover a wide array of actions that a lot of citizens would argue it shouldn't.

Example: There are many cases of Cops stepping in front of a moving vehicle when confronting a suspect, which then is used as a reason to shoot and kill the suspect because "their life was in danger". But it's very easy to argue that the Cop put their own life in danger by stepping in front of the vehicle. IMO, that should not be covered by qualified immunity, and yet it usually is.