FH is land, the house on the land is looking like crap already. At current rate, A&A can range from 500k to 3m and above depending on how extensive.
Let's face it, he is already 60. Can give him another 30 years the house will look like a ghost house. Even if he wants to pass down to his offsprings it will definitely need A&A for safety, it's all money stuck on his "FH".
Is it worth it? I find if the price is above market rate, which I think likely was offered, 见好就收, can move on.
He gave up this chance nobody is going to buy his house when Noma is ready. His house will be sticking out like a sore thumb and year on year it will get worse and he doesn't have the money to do anything.