Sure, but it's still what OP is talking about (I think). He thinks jokes that are about whatever topic involving the Twin Towers made prior to 9/11 would be banned today. I'm saying no, jokes that are about whatever topic involving 9/11 itself have been made.
Some old things may be considered retroactively in poor taste and quietly ignored, but nobody with a rational mind would find them offensive. How the hell could people in the 70s have known?