The morally (and socially) appropriate thing to do at this point would be to apologize and pledge not to use that kind of language on IRC in the future
It would be appropriate to first announce that startling has been banned from the IRC channel until further notice for violating the rather clear privacy agreements. What the folks at #lesswrong decide to do after that about altering or enforcing norms about what may be said on #lesswrong then depends on said people's preferences and any public relations concerns they may have.
My explicit use of "the folks at #lesswrong" above leads me to the more important point: Someone suitably official from here (lesswrong.com) should clearly disavow any affiliation with that IRC channel. As far as I know it is in no way official and is related to lesswrong.com only in as much as some of the users from lesswrong also have accounts there (just as some users from here also participate on RationalWiki). Those times that anything about #lesswrong has bled over to lesswrong.com the impression I've been given of the former is rather unappealing.
(It is probably unenforceable but asking the group politely to rename their channel seems like a wise move and is certainly what I would do were I a lesswrong.com authority!)
Quoting without permission was clearly a mistake, but describing it as a "rather clear privacy agreement" is not particularly apt; Freenode policy on this is written as strong advice rather than "rules" as such, and the channel itself had no clear policy. As it was, it was mostly a social convention violation. I thus have to disagree that an indefinite ban for ignorance of advice or an unwritten policy would be an appropriate or optimum response. What's happened so far- the person being corrected quite sharply here and on the channel, a...
If it's worth saying, but not worth its own post, even in Discussion, it goes here.