YES, I LOVED the idea when i had heard it as well.
It is so SIMPLE an idea but yet elegant in its simplicity. It has the added benefit of:
A. Using a plot device, the Cosmic Key, which is already a part of the MOTU mythos rather than shoehorning in some new Macguffin or other contrived device.
B. It gives a more universally derided character, such as Gwildor, a purpose. it gives him a larger tie to the universe of MOTU. It makes him important rather than a joke and i am ALWAYS for making a character more than a one off joke, just look what MYP did for Stinkor or Count Marzo.
so YES!!! please give the Cosmic Key and Gwildor the importance they deserve.
p.s. doing this will make a Gwildor toy MUCH more wanted....FYI
Ultimate power corrupts absolutely