No. "As" introduces the phrase as just one example to support "television can be superficial." The speaker could have listed more: "...can be superficial, as when the three...from a political candidate, or when vapid anchorpersons dutifully repeat the same political propaganda in place of thoughtful commentary."
If you take out the "as," we have "television can be superficial when the three major networks each broadcast exactly the same statement..." This sentence says that WHEN the networks perform this particular action, THEN they are superficial. According to this sentence, the only time television is superficial is when this happens.
Am I making sense? Here's another example:
Jim can be annoying, as when he tells the story about the fishing camp that everyone has already heard a hundred times. [This is only one of the ways in which Jim drives his friends crazy.]
Jim can be annoying when he tells the story about the fishing camp that everyone has already heard a hundred times. [Jim is a good guy, but we wish he would stop telling that story.]
Student or Learner