Although...this may be a case of your friend unwittingly creating a conflict by playing "go-between". Maybe she has a mistaken impression that she knew what you wanted and passed it along to him, then taking some off-the-cuff comment he made and passing it back to you. So, first, I'd try getting together with him directly to talk it over. Try to keep an open mind and not go into the discussion irritated. It may be a situation like that old "telephone" game where a message passed between people starts to erode quickly.
BUT...if he really is going to be a prima donna at this point, it'll probably only get worse. A professional wedding DJ would, first and foremost, want to help you create the atmosphere you want, not influence it with his or her own taste. You are not being a "bridezilla" by expecting a vendor to live up to your expectations and the contract you made with him. (Assuming you're paying him...if you're not it might make the situation a little more sticky.)
If that's the case, I know it would be awkward because he's your bridesmaid's husband, but I'd cut him loose. There would be some serious stress on your relationship with your friend either way, but at least you'd be able to have the wedding you want. I'd try to soften it as much as possible by saying that you understand his feelings and that he would like to have some license, so you don't want to burden him with trying to do something against his grain.