Counterpoint: I have opted out over a dozen times at a variety of airports (RDU, SJC, SFO, BUR). I've never been treated with anything but professionalism, and I dare say, politeness. I was asked why I was opting out by the TSA officer performing my pat-down at BUR who seemed personally curious more than anything, but otherwise it's been perfunctory. I've never had to wait more than a minute or two at most.