There is research suggesting that criminals choose victims based on physical attributes, apparent confidence or lack thereof, mode of movement and similar factors. Criminals don’t want to get hurt. They like to pick on smaller, weaker victims, but a small, confident person who looks like they could be trouble is less likely to be assaulted than a larger person who is distracted, disorganized and non assertive.
It was not the CUA victim’s fault that he was targeted, but he should never have engaged with the killer or gone anywhere with him. He apparently did fight back eventually but there was no one around to help at that point.