@Mike-And-Jane0
You're making a mountain out of a molehill. Basing your statement on ONE guest is grasping for evidence.
Sadly the 20% people would lose has already been an issue with one guest that I know of.
You are completely able to switch to Sykes Cottages or Booking.com if you prefer their terms. You can host there as well as at Airbnb, so you can just do that and the guest can chose their terms.
I have to admit that I haven't seen any guests put off by our strict policy, and I do apply it. I'm quite happy that Airbnb enforce the booking terms the contract is based on to be honest.