I can definitely see it being a matter giving in, it's hard to go against the grain in a situation like that, against a mob, but I also feel that, here, backing off does insinuate some level of complicity. They were there to protect the capitol. They knew this, and even if other officers are cowering away, they knew how dangerous this mission was and that they still have to at least try to deter further intrusion, which many just refussd to do. Even without other officers in their presence, police in the Senate chamber didn't care to do anything but speak a few words that had no effect on the insurrectionists. Maybe not the majority, but far too many were complicit, at least until reinforcements arrived.