Bananas don't keep. Apples can be kept in the proper environment for a year.
Bananas grow year-round in the tropical climates whence they are sourced. Most apples are sourced locally and only grow in late summer/early fall.
If I want to buy an apple in June, the only way to do it is to buy one that's several months old.
FWIW the article refers to Anthony Ward, a dealer in cocoa, who purchased 15% of the worlds supply during a shortage and managed to inflate global prices (depending who you talk to, http://www.tradingvisions.org/content/choc-finger-offloads-h...) enough to sell on a large profit despite considerable wastage.
He's done it before too.
http://www.theatlanticwire.com/business/2011/07/goldmans-sec...
But hoarding a perpetually renewable, perishable product? Doesn't seem likely.
The bananas I buy here in the US are flown in from South America in under 48 hours. I can get tulips from Holland in less than that. The apples number makes no sense.