It's definitely not settled science that you should never eat grains. Yes, some experts say you shouldn't, but if you're rejecting one expert because he disagrees with two others, it's definitely not sufficient to say it's "based on science".

As for dairy, while he mentioned using butter without paranoia about fat, he didn't seem to advocate for dairy. Eating dairy might be bad, but "don't eat dairy" is bad (or ineffective) advice because _people won't follow it_. Don't make perfect the enemy of better. (If it makes you feel any better about him, Dr. Carroll regularly rails against "the milk industrial complex"[0][1][2][3].)

[0] http://theincidentaleconomist.com/wordpress/finally-someone-...

[1] http://theincidentaleconomist.com/wordpress/another-blow-aga...

[2] http://theincidentaleconomist.com/wordpress/yet-another-blow...

[3] https://www.youtube.com/watch?v=hzyFZcuHmeI