Okay, so, I disagree. I see exactly what should be there for Rich showing off that he found a legit way to give Malack a constrict attack, that develops Malack's relationship with Tarquin, and hints that Tarquin is a swordsage. And he chose to do it in a way that doesn't unduly interfere with the plot.
With those objectives achieved, what should he have done differently?
EDIT: Also, Malack is wrong about grapples, too, despite his expertise. He can totally choke out Durkon with or without any fancy maneuvers. So same question: Why should Malack being wrong about grapples favor a flavorless solution over the one that accomplishes the objectives listed above?