@Linda108 Thanks for your inputs. The following quote from you is very helpful to know.
According to most posts about giving refunds just because a guest demands it, it does not usually have the desired effect.
I am just afraid that Airbnb may ask me to refund the guest for unused nights even though the guest cannot provide document for extenuating circumstances. My previous bad experience with a guest complaining room temperature and requested for cancellation.
Airbnb CS asked me how much refund I could give him even the CS knew that his refund request was not reasonable because the temperature was at 71 F and there was another guest staying in the house as well. The other guest had no complain.
The worse is that CS told the guest that I only agreed to refund him the unused night instead of a full refund. The guest was furious against me. According to the cancellation policy, there should be no refund to him even though I refunded him unused night but got a 1 star retaliatory review with all lies.
Hopefully Airbnb CS could do a good job in coordination between a host and a guest. They should stick with their policy and speak for the hosts as they do for the guests.