I for one believe that the question of whether a food service establishment has rats is very relevant to the business.
The character of the staff and clientele as well as the financial state of the staff as a direct result of how stingy their employer is can also be very relevant. Do you want to eat somewhere if the people preparing your food there will sell their morals and decency? Kinda seems likely that I could pay somebody there $100 to put their pubes into your quarter pounder.
Maybe the person only heard of the murder, saw some pictures, and didn't know about all the "justice warriors" foaming at the mouth. I know plenty of people who hardly use the Internet and certainly don't go on any social media platforms, even Facebook. We can't expect every single person to know all the details.