It was a combo not a set-up. He meant to hit Te Huna with a powerful punch and then the right but he most likely didn't expect Te Huna to drop like a sack of potatoes because of the left. He probably assumed he was going to land a hard left and then a hard right. Turns out the hard left was all he needed.
Shogun is still one of the hardest fighters for me to figure out. He has this intangible ability to win fights but he seems to win them in such sloppy way that I'm never surprised when he loses. I'm not saying that he doesn't have any technique but that he almost throws technique out the window and relies solely on his unbelievable coordination to get the job done half the time.