That's terrible but it seems to me that you accept a certain amount of risk using airbnb. How could any set of regulations cover things like swings tied to a tree?
Agreed. This is what is called an 'act of god' in the insurance world. OSHA reports that over 100 people a year are killed by trees each year. Should we regulate trees with overhanging branches in all areas zoned as commercial or residential areas? Every year people die from falling trees onto the sidewalk.
DISCLAIMER: Living life has incurs a small risk of death.
This kind of thing is an advantage of Airbnb. Our litigious society has resulted in overly sanitized public spaces - no hotel would have a rope swing on a tree because of safety/liability concerns. We need to realize that it is not worth ruining everything to marginally improve safety.