You are correct, this is a bug. Saving as draft by default works this way - it does not redirect you to All pages but remains in Edit Mode. However, when a 2-level workflow is active, obviously something goes wrong with the lifecycle.
I apologize for the inconvenience caused and I assure you that we will be working on fixing this bug for our future releases.
Thanks for the report, I updated your Telerik points.
Here's the PITS issue that you can follow: