Earlier quoted context omitted.
I totally agree that it was a microaggression, and that microaggression is a real thing that isn't to be tolerated. I know that it's all part of a pervasively unwelcoming and alienating culture that I, as a straight white male, am also disturbed by. I get all of that. I understand all of that and still think her reaction was out-of-scale.
Why? She reported the microaggression to the relevant organizers through a public channel. I don't see the problem?
As I understand it, the particular use of a public channel (particularly, the use of a photograph in it) was itself a direct violation of the Code of Conduct of the conference, and an unnecessary escalation. The only arguably excuse for such public shaming, independently of whether or not it was a violation of the Code of Conduct, would be if the act were more something significantly more serious on its own than she described (though a public complaint about the organizers would be in line if the act, as described, was privately reported and the organizers failed to deal with it in such a way that that failure was itself a hostile.)