That doesn't mean they always hedge right
Well yes and no... that article is rather simplistic.
If you buy insurance, but subsequently didn't have an accident, did you "lose" that premium you paid? Not really, that premium bought protection during the coverage period.
Hedging is somewhat analogous. If you purchase (say) option contracts for future delivery at price 'X' and subsequently the price is actually below 'X', then you've "lost" the premium you paid for those contracts, but you were also "protected" against potentially crippling price increases during the contract period.
That protection against dramatic price increases is the important part. For most airlines, when there's risk of higher oil prices it's better to pay $$$$ for some amount of protection, even if they end up eating the high cost of the hedge if the actual price is lower than the contracted strike price.
So the key is to find the best hedging strategy depending on each airline's specific situation. Delta, for example, still enjoyed
record profits due to lower fuel prices even with the large cost of hedging.