The Keyblade does not contradict it's own purpose. It's a key that is also a blade, not a giant key, even if the design was based off of a key. But the Keyblades would be useless here if you do not intend to use the Heartless as enemies.

Although I have no intention of joining this, the concept is interesting and I will be rooting for this to succeed. Good Luck and happy roleplaying.