@Christopher187 the customer service rep who told you that information was wrong.
AirBnB own help page on the room types says
- Entire homes/apartments: Guests rent the entire unit and don't have to share the space with you or with anyone else.
https://www.airbnb.com/help/article/317/what-do-the-different-room-types-mean
You define what the constitutes "the entire unit", and as long as they don't have to share that space with anyone, it is an "entire" place.
We rent out an "Entire Guest Suite". That doesn't mean the guest must be provided with access to all the rooms in my house. They just need unshared access to the rooms we define as the Guest Suite.
Lame reasoning on the part of that customer service rep. They probably just wanted to give the money to the guest and had to manufacture a reason to justify it. (Other than "the guest is being really naggy, and I don't want to deal with them any more.")