Except the bolded is clearly not the case, or if it is the case, then the police are woefully inept at estimating risk.
In most these cases, the policemen aren't 'under siege'. Of course people (inc police) can defend themselves, but it has to actually be in self defense, not simply just because you feel like you're at risk. I've said this in another thread, but a common pro gun argument is that "your right to 'feel safe' does not trump my right to have a gun". That's fine, but it also applies here. Any persons (inc a criminals) right to life trumps a policemans right to 'feel safe'.
Obviously there's some wiggle room here, because at what point does 'feeling unsafe' actually translate to 'being in danger'? This, obviously, is a problem that doesn't just apply to LEO, but to everyone in self defence situations in general. That said, we should be holding our police to a higher standard than the average citizen in these situations. Part of their job description is that they need to be able to tolerate higher risk situations better than the average person, and they need to act rationally in such situations. Right now, given that if civilians had been doing these shootings instead of cops, they'd likely be going away for a long time, it seems to me like we're holding our police to a lower standard. That's unacceptable.