Why do people jump to the most extreme side of things in discussions now a days?
There are many many many ways to disperse of a crowd that doesn't involve firing live rounds at a crowd. In fact: they were able to do it later!
Tear gas, flash bangs, barricades, rubber bullets. None of these were used until well after they made it inside.
So its sort of irrelevant to what police who were suddenly asked to hold a door from a violent mob.
With hindsight they should have had teargas ready. But they probably didn't expect the President to direct a mob to capture the Capitol.
Probably? Says who? In fact, multiple people have been shot (fatally or otherwise) during BLM protests, and actions against those officers have been very much the exception.
At least in Minnesota and Portland they let looters burn/occupy the buildings without contest.
Certainly with the benefit of hindsight, there should have been a much stronger show of force/barricades/etc. Should that have been obvious even without hindsight? Don't know.
That said, once the Capitol Police were outnumbered and things were getting out of hand, I'm pretty sure the best outcome if they had used deadly force to stop a rush would have been headlines like "Dozens of Trump supporters dead after police open fire on crowd." Worse scenarios include the police getting overwhelmed anyway and many of them killed also leading to a firefight within the capitol.
The very idea that no-one could see this coming is ridiculous.
The actual level of violence done by the mob is relatively tame. Shooting a bunch of people in the halls of Congress isn't going to stop the damage to the rule of law. And it would have what? Prevented a few laptops from being stolen, a couple doors from being broken down, etc. It's not like they torched the place.
I personally don't think violence by a mob is acceptable. But it seems most people do--as long as they are sympathetic to the cause.
Which is contrast of the “mostly peaceful” protests that involved arson and beatings.
This is just as bad but everyone acknowledges it.
If federal security at Court House shoots BLM protestors who are entering a federal court house, those security people would probably get charged with murder.
It's unreasonable to expect Capitol Police to make that sort of moral choice in the moment. And if you give cops the greenlight to shoot people to protect property, there will be a lot of unnecessarily death going forward.
That said, they may (probably?) screwed up containing the crowd contained in the first place. Though to play devils advocate, the President had just told a mob to go "wild." Not sure if Capitol Police could successfully manage that.