My understanding (I've never had the mispleasure of running a conference) is that keynote talks are very different from regular talks. With regular talks, presenters submit talk proposals, the conference committee select which talks to give. With keynote talks, the committee instead asks a specific presenter to give a specific talk.
So when someone, who is hesitant in the first place about the appropriateness of their material for a talk, is asked to give a talk, communicates their concerns, is emphatically encouraged by the committee to do so anyways, and is suddenly told by the committee that "never mind, we don't want your talk"... at best, that speaks poorly of the committee.
So when someone, who is hesitant in the first place about the appropriateness of their material for a talk, is asked to give a talk, communicates their concerns, is emphatically encouraged by the committee to do so anyways, and is suddenly told by the committee that "never mind, we don't want your talk"... at best, that speaks poorly of the committee.