I've been there. Done that. Had the house rebuilt.
Insurance pays you to stay somewhere. Did that for a while, too.
Have him hire a company to forensically list his belongings.
Granted, ours was almost 30 years ago, but the guys who did ours told us stories. Do NOT throw anything away or clean up until they get a list.
May not make any difference...if totalled, as in gone, they'll write you a check for the full value of the house, outbuildings and contents.
I found out from a guy I knew, whose house went up 2 weeks before ours...his was totalled, they wrote him the one big check, and that week cancelled him.
Seems it was industry standard, at least at the time. He was...3 years on high-cost with no replacement cost coverage.
We dragged it out, turning in items on the List, and they paid us the difference (ACV is what you get paid up front...what you'd buy the item for at Goodwill, RPC is what it actually cost, and you get the difference) until we'd passed three years. They were furious.
Tried all sorts of things, including visits to the property when I was not present.
I won.
Boy, did I win.
We just today cancelled out the Allstate, went with USAA for home, now along with auto.
Dave