Academia - What can be done to address provocative behavior by OP?

For what it's worth, I don't find the OP's site behavior to be problematic.

Fundamentally the OP did invite critique by posting the question in the first place. (This also serves as a passing comment on another meta question, which I believe is calling me to task for being overly critical of the OP's behavior, including use of the word "obnoxious." But that's almost literally what he asked for: critical discussion of his behavior.) This means that he was fundamentally more open to hearing other perspectives than someone who would not seek to post such a question.

In my dealings with the OP in the course of my answer and other comments, I felt like he was for the most part taking in what I was saying. He was also defending himself, which seems perfectly natural. I know very few people who respond to criticism (even criticism they invited) without some defensiveness.

Is (again, as the question directly asks!) the OP being a bit "mean" with regards to the student? Well, the gist of my answer (already one of my most popular answers on this site, which is a bit weird but so it goes) is yes. But again, the possibility of that is what brought him here in the first place. I don't agree that the OP is engaging on a "personal attack" on his underage student. I would presume that the student is not active on this site or reading this question, and if he is then I don't see how this would cause him any particular distress. In fact the OP doesn't say anything truly personal about the student; he just describes him as a student. Again, I emphasize that much of my answer urges the treatment of students with more compassion, fairness and professionalism than the OP seems to have evinced in the situation...but I still don't see anything out of line or inappropriate here.

I have not followed the question in question very much, but I think a more general answer is more useful and desired anyway. I answer under the assumption that your assertions on the situation are true, but this is not to be taken as an assessment of that specific situation.

There are several mostly separate issues here:

OP has been increasingly argumentative.

When he has disagreed with someone, he has added no documented or documentable information, or new logical points, he has only just cranked up the volume.

This is a typical issue. Do not let this provoke you. If you feel that no new arguments have been added, state this in a friendly manner once. Should the opponent to continue to comment, ignore them. If you feel that the comments degrade into noise or offensive territory, flag them.

OP has been hypercritical of one of his students, which is tangential to his question.

This has gotten now to the point of a personal attack on an individual student, who is under age.

If the attacks happen in the question or answer, edit them to a more neutral description, stating this as an edit reason. Should these edits be rolled back by the author, flag the respective post for moderator attention, and leave it at that.

Should the attacks happen in a comment, this comment is probably leading nowhere anyway. Flag for deletion. Should the comment be relevant, include the information in the respective question or answer and make it neutral on the way. Then flag the comment for deletion.

Sidenote: I do not think that the underage aspect should affect any of this. Whether somebody deserves to be talked about in a condescending manner is irrespective of age.

OP's "case" against the student keeps growing, ad infinitum.

Then OP should add it to the question, either by incorporating it into the text of the question, or by creating an addendum at the bottom of the question.

Addenda should be avoided. There is no reason to document the history of a question as the edit history already does this.

Apart from this, it does not sound as if the information in question is any relevant, so just ignore the respective comments or flag them. Should they be relevant, edit them to the question yourself (see above), then flag.

Should the question change to an extent that the current answers are invalidated, ask the asker to stop editing / adding information. Should this not work, flag for moderator attention.

General reaction to provocative behaviour

Slightly increasing provocations are the hallmark behaviour of trolls¹ who feed on aggressive reactions from regular users. The best behaviour is not to feed the troll: Stay calm and friendly, assuming good intention, in face of first provocations. Most trolls show their real face if they run against this. If this happens, stop reacting, and flag possibly inappropriate content. Should the provocations stop, there was no troll to begin with or they have retreated. Either way, the good guys win.

---

^{¹ Just to be on the safe side, I repeat that this is not to be taken as an assessment of the example situation.}