Why do some people seem to think the fact Cartman's father was his mother was some kind of revenge by Matt/Trey to get back at the people who were annoyed by the April Fool's joke?
It seems pretty obvious this was meant to be the conclusion........how could Cartman's data possibly have been the one of the regular characters on the show in that room? There would have been continuity problems all over. Clearly, the conclusion was going to be a clever one, not what one would expect. The solution they showed sure was+ACEAIQ- Anything else would have been forced and lame. Enjoy and stop complaining.
Yes, the April Fool's stunt sucked, but don't let that jaundice your appreciation of the cliffhanger resolution. Just my two cents.