Hedging is when you match assets/ liabilities or costs/ revenues. I.e. I sell a ticket to travel in 3 months, I don't know what the fuel price will be in 3 months, but I can lock it it by buying forward. As an airline sells tickets only a year in advance, buying fuel much further forward than that is a bit odd. You would expect a fuel purchase book to rise from about 0 a year ahead to 100% on day of departure
You could argue that by locking in fuel prices for a longer period they then have certainty over what price to sell tickets at - but the ticket price is market driven. What CX did was buy forward four years - so not hedging but a big macro view that oil prices would not stay low.
So, yes, you can say that hedging is not stupid, but what CX did was a macro gamble.