You'll need documentation of the cost to replace, hopefully, pictures from your cleaning team before their arrival, an owner's closet with lock for supplies, and limit the number of supplies you provide to a determined number.

Are you researching this yourself or asking your borrower to provide documentation to support this?

I can offer better property management services than what you are receiving currently. 

So I started creating an on boarding system where I have recorded videos and documents and protocol of how to run business.

All of the official documents I've found so far point to the national FHA requirements as their source.

The buyer is already willing to do everything you could possibly receive in court + more.  2.

Craig- you've received good suggestions here, imo.

STR insurance provides broader coverage, including liability, property damage (even non-guest-related), and gaps Aircover might not cover.For damages caused by guests, document everything (photos, receipts, estimates) and file a claim through Airbnb.

This will allow you give a reference point on how much potential rent you can receive.

The sooner you regain control, prove that you fully intend to enforce the terms of your lease, and that you will not be 'played' by their recall of events or documents, the more effective this action will be.