@Caroline1872
It's detailed in the payment terms of service ( 4.2) where they cover themselves from this event.
https://www.airbnb.co.uk/help/article/2909/payments-terms-of-service
If airbnb can't collect the payment for whatever reason, they won't reimburse the host.
It's understandable commercially and to prevent fraud collusion.
It's unusual to see this prior to a booking, there are more examples of guests abusing the system when a reoccurring payment is due during a long term booking, which leads to the question, do hosts have enough protection for long-term bookings via airbnb.
One consolation, clearly this was a guest you'd prefer to avoid arriving.