I don't ever agree with people being sharply rude, insulting, or degrading.
And there were certainly a handful of mean spirited comments to this work.
But the vast majority of critical feedback I read, and those I myself provided (including some commentary in upcoming podcasts), are fairly critical of the content and presentation.
I have no interest in degrading the author. I'm familiar with him, also. But this approach to selling agile strikes a nerve for many people because it's inhibiting, confusing, and sends a message to organizations that we ultimately spend years trying to de-tangle.