There's a philosophy in app design (not just gaming, any app), that the client is in the hands of the enemy. There is no such thing as "tamper proof". If it's on the client, it will be tampered with, eventually.
All that this does is throw down the gauntlet to the hackers and say "I bet you can't hack this!"
It's great in theory, but the concept of Blizzard pitting itself against the creative/destructive minds of mischief that is the internet hacking community is just laughable.