>Airbnb was dismissive when I contacted them about our security concerns. It apologized for the inconvenience, but said it is just an Internet company and can't get involved.

This. Happening over and over again, everywhere. No matter what your business model is, involve the 'internet', and then you are just an Internet company, and can't get involved in the problems you caused. Because, The Internet. This sets a dangerous trend for new companies that will grow in an environment where the claim of being an 'Internet Company' clears them of all responsibility.