Most people can tell the difference between a cougar and a deer. I could care less that you are a biologist. For what it is worth, I have seen a cougar once out west. Difficult to mistake it for something else. Seen Bobcats too. No way you could mistake one for a cougar.
There is a difference between, for example, a frequent outdoorsman seeing something in an open field, and a city person seeing something in the shade in dense woods. People misreport things all the time.