This case smells like parallel construction. Oklahoma highway cops are pretty aggressive, but an out-of-state license plate hunch correctly leading to a big drug bust seems implausible to me. They already knew drugs were in the car.
What you’re not accounting for is all the people they pulled over that didn’t have drugs and you never heard about.
That's the excuse Customs and Border Protection uses to make Kavanaugh stops on brown people in the 100-mile zone on the New York border.
If you're the correct dark shade of brown and have an Ontario, Quebec, or other out of state plate, a white-and-green Suburban will fly out of a hidden parking spot next to a trailhead entrance, pull you over, and start harassing you and assume you're a drug mule.