I might also suggest that whether or not it might conceivably be viewed as an attack on “the post,” it is of a different character than a proper attack on “the post” in that it is not only “uncivil”—and I generally agree civility is overrated—but effectively kills that line of discussion and likewise deprives the other poster of an opportunity to make a meaningful reply. What are they supposed to say, “Nuh-uh, it’s not horseshit because it’s not shit from a horse!”?
In short, it evidences not only extreme jerkishness (which, again, I might allow is appropriate at times), but bad faith, and posting in bad faith should, IMHO, be moddable. Personally, I think the original call was essentially correct, particularly as it was only a mod note and the response to it completely overblown.