VOA reports that the spokesman, Mohammad Younis, "said via translator that the list should never have been made public, explaining it was meant to be kept between PTA and mobile phone companies as a means to find out whether it was possible to filter obscene messages. He said a final, shorter list of banned words will be released later, after consultation with phone companies."
Many of the words on the list clearly fall under the definition of obscene. PCMag.com is pointing to one compilation that's posted here. Fair warning: if you don't like blue language, don't look.
As for why some words made the list (athletes foot?), we're too clueless to know.