I very much know what the intent was–to mock the idea that anyone could have not known what the WTC was. But for the joke to work, it would actually have to be stupid not to have known what they were. I offered myself as yet another example of someone who did not know about them, and I know that my reason for not knowing about them (being a kid and its relative unimportance to my life at the time) is not stupid, and is likely shared by quite a few people.
My contention is that the false analogy makes it fail as a parody. Sure, other people found it funny, but that doesn’t change my assessment of the actual quality of the joke. People find poorly constructed jokes funny all the time.
That said, as I said in the other thread, I did not want it shut down. You who think the joke is funny, or even believe the OP is actually well constructed, should be able to continue to have fun. Heck, in a context that wasn’t calling me stupid, I might find some of the other posts funny.