The restorations he does are interesting, but can't be justified financially. However, to many folks, they are done out of love and not logic.
So be it. That's a decision left up to the individual.
Upside: that $60k he invested into his new/old LS430 is far cheaper than a new LS500; probably approaching 1/2 the cost. And the LS430 will probably give him more miles and smiles per dollar than the high-maintenance LS500.
Downside: good luck trying to get reimbursed from a traditional insurance company for that $60k investment should bad luck befall the LS430. If it's totaled in an accident, they certainly aren't going to pay him back for his unwise emotional investment. Further, should he decide to sell it a year from now, I doubt anyone would give him $60k for it. So totaled or resale value, he'll struggle to get anywhere near his full investment back.
NOTE: There are some companies which will do "agreed value" plans; Hagerty and one other (forgot the name) which will do a pre-agreed flat rate payout if the car is totaled. I used this type coverage back when I had a 1966 convertible Mustang; insured for $20,000. Your premium is based upon the fixed coverage amount. These companies generally do nostalgic collector cars (pre-war, muscle cars, etc); not sure if they'd take on an old Lexus as a "classic" auto. This could be the answer. But, the premiums they charge are commensurate with the coverage; it's not like you're going to pay a rate based on $10k coverage and get $60k coverage. You gotta pay to play!