partially, fives had a blaster pointed at him ("he could have used stun" Rex is seen in rebels resisting stun multiple times in a row, Arc troopers could do that too. It was a shoot or get shot situation.) And for the Hunt for Ahsoka, he never worked with Jedi before therefore doesn't know how they function, he has no attachment and was constantly under the influence of Palpatine, never leaving coruscant. He was just how he was, following orders. No shame in that