We’ve additionally discovered that this hot tub was installed without a permit, and the Airbnb is operating without approval as a short-term rental, despite a county requirement to do so.
Neither of these things impress me. They are not the cause of the shock your husband received. This isn’t even likely admissible. And just even raising these issues gives them someone else to point the finger at.
I don’t know if it’s worth it to pursue because the injuries aren’t yet known. If you are feeling litigious you can get a consult with a lawyer.
The thing I think would be hardest here is identifying the negligence that led to the injury. Just because something happened at the Airbnb doesn’t mean the cause of the injuries is due to the owners negligence. I think you’ll be doing a lot of fishing during discovery.