The point of 'he is a citizen' here isn't 'who cares about goat herders', I think, but more 'see, this government will kill anyone, not just foreigners or terrorists'. If the government claims some foreigner was a terrorist and trots out some constructed evidence, how can you know any different? But when they murder someone who literally could have lived down the street from you without due process, maybe that brings it a little closer to home, and you start thinking about how questionable the whole process is. It becomes clearer given that context that they could do this to literally anyone, and clearer just how difficult it would be to stop it.

At least, that's what I think is supposed to go on here.