I agree with everyone else, but I also feel it is kinda rude - afterall, just because someone likes a song or even a singer's music, that doesn't mean they like the singer. I can think of some famous people who I may enjoy the work they do, based on what I know about them personally I don't like them. So, I'm not sure that it is obvious that just because they were playing his song they would obviously want him to be at their wedding.
Also, while I don't believe the wedding day is all about the HC, this does feel like he took the focus off the purpose of the reception and put it on himself.
But, it does appear from the article that the HC was happy about this and if his dropping by helped make their wedding reception more special for them, than that is great. And the reasons for while it could be rude are what I feel, I don't feel strongly that this is a problem - they feel more like 'what if's' then legitimate reasons why it could be rude.
So, that is why I posted the story here.