It's not a tautology. If the brain's benefit from "branch prediction" is low, then some other factor (e.g. length of code) could overwhelm the effects of predictability. So they're making a genuine claim, which is that expectation-congruence is the most important factor.

My experience bears this out. In most of my professional life, I've abided by coding standards, even if I consider the standards imperfect. That's because of the very real improvements to the team's productivity when code does what it looks like it does.