At current fuel prices he looks like a genius. If prices skyrocket again, not so much.
Delta, etc., all hedge fuel prices by using options and futures contracts.
E.g., as of today you can lock in Brent crude for delivery as far out as March 2023 for just under $60/barrel. That's a good premium over the current contract price ($37/bbl) but still well under $100/bbl.
So even if the price of oil spikes up again in the next 10 years, they can keep the average price paid per barrel relatively low.
Especially with Iran set to re-enter the oil market, the price of oil is unlikely to exceed $100/bbl again in the foreseeable future, barring a large unforeseen geopolitical event.
In part that's because shale operators have effectively capped the price of oil well below $100/bbl. Even if most of them could go bankrupt at today's prices, many others will simply replace them and ramp up production again should prices start rising again.