I worked with a guy who spent the early years of his life becoming a forensic psychologist. He told me he decided on a career change when one of the guys he dealt with was in prison for life for, among other things, killing his mother and then proceeding to eat her face off. That was the last straw he said - he had, as a hobby, been an MMA fighter and he said he wasn't afraid of anyone till he came across that guy, lol.
True serial killers won't have a reaction at all to most people. In Rochester NY there was a guy named Arthur Shawcross who murdered prostitutes. He looked like your typical Walmart greeter. Guys like him have no emotion- they don't give a shit about anybody.
We've seen Brian on video melting down, he gets all worked up with a shaky voice that cracks and talks super-fast out of panic just from dealing with people on the internet.
Watch the French toast video or when he went to Home Depot looking for Josh, he was in a full-blown panic mode about NOTHING real.
He's not scaring anyone but a child or woman.
He'd shit his pants if a real man with conviction confronted him.