you could never get away with a hard fork on this point so the best you could do is create an alternative cryptocurrency which you would then become the developer of instead of bitcoin.
Why not? All he'd have to do is code the change, offer it as the new version of the "reference client" and see how many people accepted it. What percentage would have to accept the hard fork for it to become viable? 50%? 20%? 5%?
Lowering the difficulty of the real, as in original, bitcoin, so the rest of us can go on mining the original, high value per coin, international settlements bitcoins while he goes on to make a payment network for people to buy popsibles with. Sounds interesting... Especially with everyone having their coins from the past still exist on both chains, the original and the new popsicle-coin chain.
-MarkM-