I think you're supposed to read "a random person" as "any random malicious person".

What prevents the violent psychopath from killing the child they see to get their lollipop when they want something sweet? The fact that there are repercussions. What prevents those that have no qualms about stealing from a store from doing so most of the time (even those that steal don't do it every time they enter a store)? The same.

Besides moral decency, I said. What else do you think there is?

It seems like consequences are the only language that bad actors understand, unfortunately.