I’m surprised it passed a home inspection without being condemned. Looks like even the studs would be infested with termites. I don’t know the regulatory framework in his area, but in many places he wouldn’t be able to get a certificate of occupancy to allow him to live in that dump.That house looks so bad, I think it would actually be cheaper to bulldoze it and start over. Or just buy land in an empty field and start from scratch.
This is a real life "Ship of Theseus" thought experiment: I don't think there's a single part of that house that can be salvaged.