OK, you just haven't read Lawler far enough. ^_^ Try his post on conversational deletion. This happens when material understood from context is removed without lost of communication. Note that "Are you doing?" is not possible because material is removed that is essential to comprehension. Whereas the "what" in "The f**k are you doing?" is obvious, "Are you doing?" can have any number of introductory fragments.
– Robusto 2016-11-28 22:21:42Z (my bowdlerization)
The comment was not deleted by a moderator. As the person who is recorded as deleting it is not a moderator, it will have been deleted by flags from the community.
Sumelic has commented that it may be possible for a comment to be deleted with a single flag; normally it takes two, or even three. At present, the information available to me is anomalous — it appears that the comment was removed by a single flag which should not (to my mind) have had that result.
Apart from the fact that it should have been an answer, I can't see anything objectionable in the comment. I would have restored it with this Meta answer, except that the system doesn't make that possible: we can only undelete mod-deleted comments. I'm investigating how that might be achieved in this case.
This may be an opportune time to remind members that this site exists to serve an academic interest in the English language. English contains words which in some circumstances can be offensive. However, the academic discussion of offensive words is not, of itself, offensive. If you find you are offended by the mere mention of such words, rather than their use, just walk away from the question.
This is also an opportune reminder that content — comments, posts, or entire questions and their answers — can be removed without any moderator intervention whatsoever. And to say again that comments are ephemeral and can be removed at any time. As it stands at the time of this answer, I can't see a reason that the comment should be removed, but that doesn't mean it's immune from the normal operation of the site. It may end up deleted by further flags, or removed from the post but preserved in a chat room, or just deleted anyway. If a comment is worth preserving indefinitely, it's worth expanding into an answer, especially since it may not be possible to restore a comment if it's deleted.