Shouldness in "Rationalists should win" is a much more detailed notion than correspondence to winning situations. It refers to a property of achieving goals, as seen under uncertainty, in our case implemented by cognitive algorithms that search the solution-space for the right plans. Rationalists should-win, have a good measure of win-should-ness.

Looking over it all again, I should add that "rationality is about winning" is also an immensely simpler sentiment, that still seems to retain the gist of the message for which the "rationalists should win" motto was devised.