Being a disadvantage just isn't necessary for a comparative advantage.

The critical piece necessary for trade to be profitable is that each party can produce a good at lower marginal and opportunity cost than the other party. I was thinking of just the absolute advantage case (like the example you gave and the example I gave) where one party's disadvantage becomes an advantage in the presence of trade, but I believe it's correct to refer to two parties which each have an absolute advantage as comparative advantage. I'm not sure about that, though.