With what TSA agents see at airport security on a normal day, you have to be doing something pretty special to be firmly told 'what the hell are you doing to my line?'.
The people in question had made a few standard mistakes. Despite waiting for around 15 minutes before even getting to the trays and conveyer, they didn't put any of their liquids in a separate bag. They didn't get the laptop out, they didn't take off their jacket or their shoes. They didn't do any of this until the very last moment when hundreds of tired travellers are watching them with contempt. To top it off, walking through the metal detector with a belt on and a pocket full of change.