Not any different than the very common older, white racist character in sitcoms today. They're funny! Not because racism is funny, but because the unacceptability of their racism is funny.
FWIW It's Always Sunny is, I believe, considered the longest running live action sitcom. Longest running sitcom overall is The Simpsons.
The Simpsons is most definitely a sitcom, just one that happens to be animated.
If you opened a textbook on mass media, it might have a definition of sitcom that is more culturally relevant.
A square is also a rectangle.
I guess soap operas don't count?
I'm not sure it's our job to keep adding qualifiers to the OP's bold statement that "Simpsons is not considered a sitcom, but it is the longest running show, period." until it's finally accurate.
In any case... PBS' Nova is 47 years old. Frontline is 37. I believe those are aired in prime time. And they are "not considered a sitcom" either.
I think the problem is that a lot of the humor in Airplane has aged like sour milk - it's not a comedy made to stand the test of time. Consider "Blazing Saddles", which does not suffer from this problem nearly as much and is 6 years older. I could see it getting made today just fine with a few tweaks.
And Blazing Saddles is the poster child for "could not get made today" arguments.
Blazing Saddles was the poster child for that when many of the movies that argument is now made about were made, too.
Because its the kind of movie that could never be made, except that it was. And if there was a Mel Brooks-in-his-prime now, the modern equivalent (which, presumably, Blazing Samurai this year will not be) could get made today.
That's not the biggest change: