I personally can not stand DD but rather I like him or not. You are giving away commercial themes which makes them ripped themes and illegal. You have not gotten permission from him and under the GPL they are still considered commercial themes.
He does not have to reply to you or anyone else concerning his themes. Just because he has ignored you does not mean you now have the right to rip his themes.
You should remove them from the site. Unless of course this site is known for ripping peoples work then I guess it wouldn't matter.
My personally feelings on the matter is to late you've already passed them out and in my book a theme ripper. Maybe one day you'll actually make something of your own then others can rip it and remove your copyrites claiming it as there own.