Are we talking about the same Alizée that we are fans of? The one who shares the stage with other singers and dancers so often?
In this case, they wouldn't have been sharing the stage. It isn't like people buy the tickets, show up and then have to choose between which star they will see. The dance class is with A&G. That's what people are buying the tickets for. Like people buy tickets to the Superbowl to watch the game, not for the halftime show. And if they came for the show, NFL and the teams would still get the same money either way.
I just can't see how this side show takes away from the the dance instruction session or would affect Alizée. And the whole thing doesn't make much sense, so there must be more to it that we don't know.