This is a little bizarre and not something I've run into before. A guest did an instant booking this morning and I thought everything was fine. He sent me a message this afternoon to ask if it was ok to check-out a day later. I told him it's no problem, I can amend the booking as we have availability.
He then wrote: "Will I be charged an additional day though? Typically with hotels we don’t get change for the checkout date?" (verbatim, C&P)
I thought he was having some fun with me and said we would need to charge him for the extra night. I haven't heard back from him and now I'm a little concerned that perhaps he was deadly serious. In this instance, I think I'd prefer that he cancelled his reservation... or if I could do so without incurring the wrath of Airbnb's Host cx policy and lose my Superhost status.