I don't buy your argument. All homebuilders were at one time non-hombuilders. Winning a RV-12 kit might provide the motivation to convert one more non-builder to builder. I don't see a kit discouraging anyone from entering - you do realize the win a plane sweepstakes is a no obligation contest? No purchase or donatation is required.
I agree, which is why I would sell an ICON A5 ASAP or trade it for something I CAN use. Tax liability certainly won't stop me from entering.