I think the comment you are replying to is saying that the area the cops let those people into was either already over run and they were moving to a different place to keep people out. Or that it was area the people were allowed to be in, hence the other non cops in the area and so it’s not a problem that they were let it. Not that the cops were just abandoning there job and letting people into an area they shouldn’t have.

I have no context for where this is and if it’s true but I think you are misrepresenting the above comment.

Six policeman are unlikely to be able to hold a crowd like that back. They were probably told to fall back to concentrate their forces elsewhere. Removing the barriers prevents injury to the crowd.

The Capitol Police seemed to be very ill prepared to deal with events today, which is quite sad given that the protest at least was no surprise.