If he truly doesn’t know then I doubt he’s a real butcher.
This is one of those cuts of meat which butchers kept to take home since most of the general public had no idea how flavorful and inexpensive it truly was. It was underappreciated for many years by everybody but butchers.
But then Fajitas hit popularity status and hanger steak soared in popularity.
So, he’s either feigning ignorance so he can take it home for the family or he really is a hopeless dumbass and a disgrace to the butchers profession.
I second the motion to find a better butcher.