I think it’s fair to be disappointed, and I’m even open to the idea that the conference organizers fumbled. But yeah, the attempt at public shaming feels weird in light of the scant details. Calling out misbehavior is sometimes appropriate, but it kinda requires the accuser to describe exactly what happened.

I know absolutely nothing about the specifics of this incident (I don't even know who would have made this sort of decision) and it seems overblown to me as well. I wouldn't say "silly", because I don't discount the feelings of disappointment, but this stuff happens all the time without nefarious intent. My reaction as an outsider (and I have to reiterate I really am an outsider--I know nobody involved) is that this really isn't a big deal.

Just, from the conferences I'm familiar with, while being a keynote speaker might have some status associated with it, a normal track talk is more legit than a keynote talk, just comparing talk with talk. Everyone know the keynote is invited, and they're talking to fill the space, not because their idea is so important it needs to come out now.