There are two approaches to this question. One is about my right to sing whatever I want to sing regardless, the other is about my responsibility to consider the feelings of others. It's true that people have no right to be upset if I sing a song that they've invested a lot in trying to learn - but that may not stop them, in real life, feeling hurt or being left with nothing left to sing if I do. So do my rights to do what I want outweigh my responsibilities to consider their feelings even if I feel those feelings make them over-sensitive? It seems to be quite a relevant question about society in general!