Probability in a given encounter, is how the post is written, which is fine. That is, in an encounter between police and non-police, it's much less likely that a police officer is killed or injured than that someone else is.

Now, police officers are obviously going to be involved in a lot more of these encounters than the average person, and there are fewer of them, which I think is what you're getting at, but this is valid from an "in a given encounter, which party is more-justified in fearing for their physical safety?" sort of way.