While it's great to vote and encourage voting, demanding every 20 something popstar divulge who they're voting for so you can decide whether or not you support them anymore is one step closer to Idiocracy territory.
You may not be interested in what any "celebrity" chooses politically, but there are huge groups of (stupid) people who let the people they like/follow dictate their choices.
As much as the Idiocracy of this is apparent, I don't mind because it may get more people actually involved.