Actually, I can tell his basic point is not to have attack transients out of phase with each other, but that's kinda crazy because they're far from similar, a kickdrum and a bass. It makes me want to go,
"Naturally, you're familiar with the process of assigning each sound contrasting wavelengths so the periods of possible cancellation as the attack transient progresses are kept brief?"
...which of course is the 'carving a hole in the bassdrum to put the bass guitar in' technique, from various mixers including Ted Templeman. The one centers on one bass range and higher beater click, the other occupies midbass space and avoids stepping on the bassdrum's frequencies. Some guys (I'm thinking of Brad here...) seem even able to do this in mastering, probably by digging out different narrowband bass boosts.
Of course, this trick of getting the kick and bass to blend densely by not allowing cancellation between bass frequencies is a LEETLE more sophisticated than 'moving the speaker cones in the same direction at the same time'...
