I still stand by what I say. I think the rules should be totally independent of the debate. Both types of engine should have to be equal in displacement, noise requirements, and any other regulations that may apply. If the rules are THE SAME for both engines, then the better engine will prevail.
But, I think the four-stroke fans would bring up the following point. Why do we choose displacement as our standard? Why not regulate them to be same-horsepower instead? I can't really think of a philosophical argument that makes displacement an intrinsically better unit of standardization than horsepower, except that it's more common. For many years, motocross was equal-displacement. NASCAR runs equal-displacement for all competitors. Formula-One runs equal-displacement. Now, it's also true that none of these sports have two-strokes at the start line to mess things up, but I think the core thinking is the same.
When you start with equal displacement, the tuner becomes like a painter in some painting contest or something, with the same canvas as his competitors. His goal is to make the best painting (power) he can. If you regulate the horsepower instead, then you're telling every painter to create the same painting using as small a canvas as he can manage. Which sounds like the more artistic and interesting pursuit? Which is a better test of painter and paint?
So, I guess I did find a philosophical argument, after all. Yay!