Minimum stay if Friday/Saturday included

For my chukar property, chukar – ORP246282, I set up a season "fall and on" and used the Length Restrictions with a 6 night minimum required if Friday or Saturday is included in the stay. Thus, for example, if a guest tried to book Thursday October 1st to Saturday October 3rd, the system should say a 6 night stay is required.
It does it correctly in your system here:
http://heavenlylodges.hosted.ownerrez.com/heavenly-lakeview-lodge-orp5b3c20ax#availability
But I set up an API integration to a new AirBnB listing and it didn't work correctly. It applies the 6 night minimum stay to the arrival day of Friday or Saturday, instead of if a Friday or Saturday is included in the stay.
https://www.airbnb.com/rooms/42223715?

How can I fix this so it works correctly in AirBnB?

The way AirBnB displays availability is not what it should be. Definite PITA for many of us. I'm not sure what your goal is (maximizing nights booked, not splitting a weekend, etc.) but would it help if you said all bookings had to be a minimum of 6 nights but then did Gap Nights with a minimum of 2 or 3?

Unfortunately, this is a limitation of Airbnb (and HomeAway as well). They evaluate min nights based on arrival day only. I'm not sure why.

OwnerRez for direct bookings evaluates min nights based on every day of the booking. For HomeAway we actually enforce this via API because they allow us to pass back a "stay not allowed on that day" message to the guest. But Airbnb only has a "this is unavailable now" message that would be very confusing to the guest, so we let their rules stand.