You are correct, but that is only part 1. Part 2 is that you cannot simply "neutralize the controls" and redirect your flight path a second time, back on track, as described in the picture.
I guess we went around the world to [hopefully] agree that the slip drill could be accomplished with the same flight path changes drawn, nose basically on heading, but with a corrected description of how to move the controls to accomplish this. This may seem like splitting hairs, but verbatim, that drawing and description defy the laws of physics as I understand them. I do not feel this thread I started is very important, I just wanted some input on that picture and wanted to try to understand how others were thinking about it.