It's not uncommon in other areas, such as food, for people to be prematurely dismissive - such as "I don't like Chinese food" or "seafood", or whatever, based on having eaten one or two dishes and being put off it. Is it possible that your friend is in a similar situation, where actually there is music he would like except that he made his judgement before he discovered it and hasn't allowed himself to re-evaluate his opinion since then?
I have listened to a wide range of music and I don't care for any of it. Some African chanting is interesting but more in the way that crashing waves where interesting than any real emotional response.
