The U.N. (as an organization) is always in a weird position, if they take a hard stance on something they risk their own existence. Saying they will investigate the allegations is reasonable, altough immediately firing the people involved is a bit too much.
most places in the world require that you have a license for tourist renting. In theory, they inspect each unit before giving the license, to make sure it is safe. And in theory airbnb requires that license before allowing you to list on their site. If you don’t have the license, you get fined, same as if you opened a store without stablishing a formal company