No answer posted so far in reddit.
Too little information. Invite him here and we will see.
Only one house and want to FIRE? Is the house in Hillsborough/Atherton?
Plenty of places to go to FIRE. Many in the east bay. I am 150 miles from the bay, life is easy and affordable. You can live in Tahoe easily on $40k a year. Houses still available under $400k that are very nice. Easily could retire here or anywhere USA with $1m cash if you owned your house.
If you can’t fire in Bay Area, continue working or investing or landlording. It would be too much risk. You should make enough to FIRE in Bay Area and then move to a cheaper place so that you have 2x or 3x for out of BA Fire. If he needs to sell the BA house, he needs to continue working but he can work at a leisure pace of 75% load, don’t overload yourself