Just as no-one would begrudge a dominated race from poking fun at the dominant race, I don't see why you are so on your high horse about the dominant age group getting the same. 'Punching up' is fair game where I come from.
I'm afraid I just don't get your outrage at an innocent comment poking fun at the most dominant section of society. But, as you're the second person to have taken offence, I'm going to delete it anyway.