We have no idea who the creator of the sign is, and we don't have any idea if he actually was given a moose -- however I'm sure Ghostcrawler will want to hand deliver him one after reaching international fame and stardom from this brief moment on the Colbert Report.
A larger image, full of more truthiness, can be viewed here. You can also view the entire Colbert Report episode over at Hulu. The moose sign comes in around 20:43.
Many thanks to Sean for the tip!