Great reply! Just wanted to check .... did Richard Miller say it's AFTER the yawn or do you mean at the tail-end of it? I'm guessing the latter... so the yawn is still used to explain the feeling, is it not?

Yawning, sighing, vomiting, "the dumb sound" - these are all natural functions that enforce a bigger opening of the throat, that is, soft palate high, larynx low, pharynx wide.

IMHO referring to these natural functions are okay, even necessary. However, the instruction doesn't stop there. Ultimately, the voice needs to sound beautiful. Doing these natural functions, like yawning, alone won't achieve a beautiful sound so there will be loads of tweaking left to do via vocal exercises, explanation, experimentation, etc. My 2c