I agree it seems like a disproportionate act to take given the situation as the author described it, but this certainly does seem like the kind of scenario that involves a lot of context that goes unmentioned.

One explanation for this sequence of events is that the conference planners had since found a new compelling topic reflective of the project's direction to be covered in a keynote speech, in which case the natural topic to replace is one that discusses a "possible"/hypothetical idea. I'm sure there was a better way for leadership to handle this, in particular around communicating their intentions, but this shortcoming seems much more likely a case of incompetence rather than malice towards the speaker, given the lack of information to support the latter.