Then I have to ask you: If all the cops are supposed to do is stand there breathing menacingly, how are they supposed to stop the angry mob?
Without any kind of cop/ss protection, this mob would have went berserk on whatever politician they'd find in that building, there's simply no argument there.
The cops/SS had to use force at some point. Teargas, rubber bullets and so on were used before the mob entered the building. I doubt that rubber bullets are standard issue for the kinds of guys in charge of security inside the Capitol and they clearly had no teargas or anything else. The secret service drew a line and shot the person trying to step over it. She got shot. It's shitty that she got shot, but it was a really stupid thing to push your luck to that point.
You're saying that the police were in place and would be able to stop the mob from crossing a line. They did. Turns out, they didn't fuck around with their response.
And just to clear something up: I'm not happy that she died and I'm not saying that she deserved to die, but if you allow me this level of callousness: It falls under the rule of "Fuck around and find out" if you ask me. She gets the same amount of scrutiny that I was using for antifa and BLM riots. She doesn't get a bonus for being from the other side of the political divide.