I don't believe this is correct. If you want to change lanes, you engage the turn signal, Supercruise will show blue light. The blue light denotes Super cruise is paused while you change lanes. After you've changed lanes yourself, you wait for the light to glow blue again so Supercruise can resume.

Here is a video from Cadillac showing your statement is false: https://www.youtube.com/watch?v=_rxW68ADldI&t=0m39s

Tesla will speed up or slow down and change lanes automatically. This is not the same. Also, Supercruise is only enabled in very limited circumstances. You can use autopilot anywhere even if it isn't officially recommended.