Separate the Art from the Artist?

In today's USA Today, Michael Medved pontificates on the evils of actors mixing politics in with their work. Specifically, he criticizes Viggo Mortensen for making the most of his new found celebrity as Aragorn from Lord of the Rings to protest the war in Iraq. Medved, who himself at some point parlayed his minor celebrity as a film critic into a prime role as conservative social commentator, claims that Mortensen's off screen antics "interfere with the entertainment value of creative work."

I guess Medved can't separate the reality of Mortensen's politics from his role on screen. That seems to be more Medved's problem than Mortensen. It's also the narrow-minded mindset that will keep people from recognizing Sean Penn's work in Mystic River because of his politics or burn their Dixie Chick CDs when one of them shoots their mouth off - regardless of the quality of their art. Artists frequently produce things that don't match their own world view or politics. Any artist who let his or her politics bleed into their art consistently would produce work that became tedious very quickly. So if the artist can make that distinction, why shouldn't the audience?