Not exactly a bug or a feature… just the “naive implementation”.
The idea of resetting the tempo has come up before. I wrote about it recently in a thread about Auto-Tools improvements I’m working on:
Coincidentally, I had some middle-of-the-night ideas about how to make this work, even before I saw that you’d posted this. So I’m going to try and see if I can get this going in the beta soon, hopefully in the next few days.