There was somebody who circumvented the intended governance structures to make this happen, and this is probably where the frustration and this blog post come from.
They could (or should) have been more transparent with communicating their reasoning, but again: Anyone who has ever organized any decently sized event knows that in the end the buck will stop with whoever has to do the actual work. And if you ask me (you probably didn't), giving organizers that power and trust is generally reasonable. They have the best insight, they have to carry the consequences if it does not work out, etc.
Of course that trust can be lost and a community can decide to let other people organize their event next time. But the way I see it those made responsible for an event should be able to shape that event.
You still seem to be missing the point: Which “organizers”? The ostensible “Leadership” of the project – which one would think should be the final arbiters of any such organizing – did want the guy to do the keynote. The real issue here is that the stewardship of the whole project, to put it in sophisticated technical terms, sucks if some grey eminence can undermine the official leadership just like that. Then their whole code-of-conduct, leadership-by-committee, woke-and-adapted-for-Modern-Audiences governance foofarah is just flim-flam, a sham, a lie.
That's the real issue here.
Of course that gives them a certain level of power of the discourse, but what is the alternative? Community-voted conference structures that fail to take many variables into account that you need to take into account for an enjoyable conference?
If I were invited as a keynote speaker and the conference organizers tell me that the stuff I produced is good, but not suitable for the keynote I wouldn't blame them, but myself. The only instance I could imagine was if they invited me specifically for a spicy topic and my talk was too spicy for them. But a tech talk? Come on.