My interpretation of the guidelines is that you shouldn't use accusations of astroturfing against a specific comment you disagree with, because you cannot know

My interpretation of the guidelines is that you shouldn't use accusations of astroturfing against a specific comment you disagree with, because you cannot know in any particular instance whether or not it is indeed astroturfing. I don't think the guidelines are meant to ban all discussion of astroturfing in general as a marketing tool.