The subtler point of this article is that a simple no is a good test of your authority- service personnel, students, people he had power over; they had to except his "no." Girlfriend? Not so much. The power in question isn't the added power of using the word- it's the way the word reveals the power dynamics at play. He didn't gain more authority by using the word; the word revealed to him his authority and its limits…
Reject duality. "Yes" and "No" create each other. They are both to be used, in harmony.
This article is really about honesty. Eliminating posturing and the little face-saving nothings from "No" half-way empowered the author. But at the end, he found it was not enough. Now, he must find honesty in "Yes."