I don't have any trouble believing it. It's surprising how many things can be unknown by people, even intelligent people who are otherwise well educated, and who even have some experience with chickens.
Just for an example, there are many people who don't know that in chickens the mother determines the sex of the offspring (because many people learn about the mammal XY system and are never told that any other system even can exist. So they assume that all animals use the one system they learned about.) A person can raise chickens for their entire life and never realize that, unless someone points it out. There are many other points that are equally obvious after you know them, but not obvious if you don't know what to look for.