Here's my reasoning. Most PRs don't know when they successfully stop something. Doctors, Roleblockers, and Jailers don't generally know that they have protected or blocked something during the night. Scum most likely thinks that happened since the chance of one of those roles existing is pretty high, rather them shooting the 1 player that may have some self-protection.
However, they did that, so I know for a fact that I was the one that was targeted. I figured that could be useful information, and why I'm looking closely at people that currently scum-read me.