I have no idea anymore what's being talked about here (maybe I shall now read it all again!), suffice to add:
Generally I am in agreement with that. You are offering a service which the couple are paying for. Sometimes I've had to play things I don't like or don't necessarily think are appropriate, but I think it would have to be exceptional circumstances for me to refuse outright to play a certain piece. I would rather try to work with the couple to provide what they want (for example, recommending that a piece might sound better on the piano, or possibly better if they had a recorded version). I might not like what they choose, but if it was within my capablilities and they were paying the fee, then I wouldn't object. I came across a couple who had dreadful trouble with their wedding music recently and I didn't think that what they were asking for was that obscure; possibly just not 'run of the mill' wedding music. Nevertheless, they had given their choice of music a great deal of thought.