He didn’t. There was no bottom three last night. Ryan kept “randomly” sending people to the couches as safe. Scotty was paired up with Casey at the end to create suspense — Scotty was never in any danger of leaving. I suspect that they did it this was because the bottom three was the obvious trio of Jacob, Casey, and Haley, and due to the complete lack of suspense, they sent people back to the safety of the couches in no particular order.
Of course, many people thought that Scotty was in the bottom three, and that will probably make his fans vote even harder next week. And Haley’s voters may relax thinking she’s safe. Keep in mind the infamous Idol moment when Ryan told Judd Harris to “sit down” but didn’t follow it up with, “you are safe”. After telling the remaining contestants that they were safe, Ryan said, “Judd, you are going home tonight” as the camera caught a shocked (and seated) Judd Harris taken completely by surprise. When Ryan doesn’t say something (like the words, “you are in the bottom three”) that’s just as important as what he does say.