You shouldn't blame the guest who cancelled the accomodation without understanding the situation (flight cancellation from South Korea due to the outbreak). Airbnb which is the platform between the host and guest is the one that provide approval for the guest to proceed with the cancellation due to the COVID 19 crisis. I understand that you might be fraustrated becuase of this issue and the impact on your business, but you shouldn't send me that unpleasant and sarcastic message.