@Anonymous,
It's scary to hear about these types of events with guests. However, the people had been hosting for seven years, and I noticed that they didn't mention that they had STR, homeowner, or business insurance for their rental. It appears that as long as they were getting paid and didn't have significant issues that they didn't bother to address the fact that the Host Guarantee clearly stated it wasn't an insurance, and continued hosting with those blinders when the scheme was rebranded as Air Cover.
My homeowner insurance company would have given the choice for the policyholder to pay for the hazardous waste testing and clean up (and repairs/replacement), and then be reimbursed, or allow them to coordinate that work with their preferred vendors who must also provide warranties. The policyholder would be responsible only for their deductible.