The cops didn't open the barrier. Someone (Anifa?) picked it up and ran away with it. The cops didn't have very good security though.
I respectfully disagree. Show me the exact moment a cop moves the barrier. I saw this from a different angle. Someone in the crowd picked up the barrier and there was a scuffle over it.
Did they secure the area properly? No. Did they seem to fight really hard to not let the protestors in? No. But they did not remove the barrier.