For them to do this when a beloved public figure is involved, it has to be a grave situation and not just an incident here or there. Some other notable figures (e.g. Martin Luther King Jr, others) have been accused of plagiarism in their doctoral dissertation but it never rose to this level.

The reporting is that plagiarism occurred on 2/3 of the pages of the thesis. This doesn't mean that 2/3 was plagiarized, but that he included plagiarized content throughout. He may genuinely be capable of this level of research but did not actually do it. As reported, this is an appropriate decision.