I have seen that washtowel about not listening to rap or heavy metal. It hasn't started with that, either. They have always been against anything that is popular. Back in the late 1970s and early '80s, they were bashing rock music, "that evil disco", and funk music. Anyone that was young in the late 1960s probably knows about how the washtowel felt about the Beatles and the Rolling Stones. Before that, it was Elvis Presley and rock music in general.
Not to mention, if anyone goes along with the rap and heavy metal (including Led Zeppelin, which they classify as heavy metal), they go after songs on flimsier and flimsier grounds until you have only 151 songs you can listen to (that number is subject to change if they add or delete Kingdumb maladies). Out of which I have found some that were every bit as "bad" as many pop songs, yet they will not throw those away the way they made me throw out the good pop songs.