So far it's the only addition that has been treated that way. For the backstory, Brian switched to SONAR last year and loves it. The loop library was always intended to be a commercial product, but I was able to persuade him to let loyal Platinum upgraders to get it for free for one month. He graciously agreed.
It is true that anything that happens in Platinum becomes part of Platinum. I believe that one piece of content has been the only exception.