As a general rule, if you see a user behaving in a way you feel is inappropriate, flag for moderator attention. That's one of the things moderators are here for: to handle situations where the problem is with a user rather than with a post (cf. off-topic questions, for instance, which don't need a moderator in order to be handled effectively). From the 'be nice' policy (emphasis mine):
If you see a hostile interaction, flag it. If it keeps up, disengage — we'll handle it. If something needs staff attention, you can use the contact us link at the bottom of every page.
In this particular case, the matter was brought to my attention by a "rude/offensive" flag on the initial comment from
Richard Valorum, which said:
The firestarter in me is tempted to close this as a dupe just to see if we can provoke another user into having a meltdown.
(For the record, this was not meant as an attack on you, but as a reference to another recent question about Dementors whose closure as a duplicate has already spawned two meta posts and a great deal of ranting from the OP of that question.)
By the time I saw this flag, you had already responded with another comment:
@Valorum "The firestarter in me is tempted to close this as a dupe just to see if we can provoke another user into having a meltdown." So you close down questions merely to annoy others? That comment of yours, Valorum (formerly known as Richard), says a lot about your character.
This was obviously a fight waiting to happen, so I deleted both comments and wrote a short comment of my own asking Richard Valorum not to make inflammatory comments. Once he'd (presumably) seen my comment, I deleted that too, so no evidence of the drama remains on the question. You've now created a permanent record of it here on meta, but there's not much I can do about that.
For future reference, if you see inappropriate behaviour,
flag it rather than engaging the user. The moderators are here to deal with this kind of thing, and we'd much rather have to reprimand one user for a single inappropriate remark than two for an extended argument.
And no, I'm not going to undelete the comments. The entire chain of comments was unnecessary and borderline offensive, and leaving them in place would only have encouraged further drama and possible escalated the situation.