The names would have come out over the next few days, anyway. McGonagall’s choice was to either break the news to all the students on her terms, or to have wild rumors appear within hours.
Breaking the news herself gives her the chance to declare her solidarity with the affected students in the clearest possible terms and to quench any schadenfreude immediately. She is proactive, rather than reactive. In fact, compared to the Minerva McGonagall of the very early chapters, she feels a little more grown-up now, in a way. She has developed into a more sophisticated character over the course of the story, and I like this a lot.
You're right, she should have listed them as she did. But she still needed to have told them privately beforehand.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 117.
Plans for next chapter release:
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)