It's true that the author just scratches the surface of a very large topic, but I appreciate the attempt to start a discussion. I've gone around and around different aspects of this situation with people from several different backgrounds, and have dug myself into many different holes, so I'm not coming here with a simple response, but instead a long list of questions.
On one level, all citizens of all states have a responsibility to understand and deal with the actions that the state takes in their name. As a citizen of the US, I am at least nominally complicit in the actions of my government. I may not approve (indeed I often don't!) but I do recognize a certain kind of responsibility.
But this isn't really what the author is about here - he's asking if artists have an extra duty to speak because of their position in the culture -- that their words carry a different kind of weight (possibly even a different weight than the ubiquitous "celebrity" speech). Do we think that artists have a more powerful obligation to speak out about issues other than their own field, because they are artists?
(I don't mean to devalue some celebrity work -- we've all heard some very articulate and persuasive testimony from popular/famous individuals, and seen some of the great work they do in all parts of the world. But the kind of attention they are able to bring to a topic is fueled by a different kind of fan base than I think the author here is discussing)
And in the case of these two artists, we're talking about different countries with different political situations than we have in the US -- without going into complex detail, I have to admit that both Dudamel and Gergiev are dealing with a myriad of expectations from multiple sources. Neither of them are dancers, but they both walk some very sophisticated choreography.
I'd love to dig a little further into this topic, but don't feel like I want to swallow it all whole -- it's a big, big mouthful.