Captain Birdseye, you are completely correct when you say:

the artist has a right to decide his own repertoire.

And it is also correct to say that "The organiser has a right to specify the program he wants when he speaks to talent."   If he wants to do it, he's within his rights to say, "I only want Chinese or Ecuadorean songs."

And the singer involved is completely within his rights to tell him, in emphatic tones, "Up yours, Jack!"

Dave Oesterreich