Don't ask if you are responsible. You can be at not fault but desperate people will sue you.
Ask if injured, WHO IS RESPONSIBLE?
Clearly neither you or he would pay out of your own pocket. Somebody has to pay, that leaves either his business insurance or your home owner insurance. There is no other way.
So ask him about his insurance, get his answer in writing. So if he provided the wrong information, he can't sue you.
And ask your home owner insurance to see if they cover this as well.