Instead of the somewhat fuzzy method of dating via news, couldn't they combine this approach with that recommended by Errata Security to use bitcoin as a public ledger? http://erratasec.blogspot.com/2013/05/bitcoin-is-public-ledg...
You could (conceivably) make up plausible future stories, but not things like quarterly results, lawsuit outcomes, etc.
You used bitcoin as an example because of your fanboyism. In no way is it obvious to use a currency or it's surrounding infrastructure for this (non intended) purpose.
Actually, I didn't. Next time you attack someone, make sure it's the right person. Dick.