Not having a solution doesn't prevent from criticizing an hypothesis or theory on the subject. I don't know what are the prime factors of 4567613486214 but I know that "5" is not a valid answer (numbers having 5 among their prime factors end up with 5 or 0) and that "blue" doesn't have the shape of a valid answer. So saying p-zombism and epiphenomenalism aren't valid answers to the "hard problem of consciousness" doesn't require having a solution to it.