I understand where he is coming from. His emphasis seems to be about not controlling the speech, which works well for me. If I have something practiced or have a grading scheme that I am conscious of while speaking, the outcome is great or terrible. If I mess up a few times, I fall apart instead of picking up the pieces.

Advice like his has drastically reduced 'umms' as a by-product, as it is a byproduct of my nervousness. If one is giving enough talks that the umms are not a tick but a habit/crutch, then it is definitely something to be targeted.

tldr; I think his advice on umms is due to the 'normal people' aspect vs. public speaker.