Add ctrl pt to orthogonal line makes it a bezier? Why?

(Running 7.2.1 on 10.11.16 El Capitan)

Let’s say I have an orthogonal line connecting two shapes. Now I want to add a midpoint so that I can drag the line out a bit to make a U rather than L path. In preferences I have Line Editing set to double click to add a point. If I double click on my orthogonal line, it turns into a Bezier line!!! What? That can’t be right. It didn’t do that in OG 6. I do this sort of thing a lot. Okay, so now I undo and try again. This time I bring up the context menu on the line and select Add Midpoint. Now it works correctly. I get a new midpoint and the line remains orthogonal.

This has got to be a bug. Or did someone decide, INCORRECTLY, that the only reason to add a midpoint to an orthogonal is to make it a bezier? To make matters worse, I’ve got no way to set a keyboard shortcut on Add Midpoint, so I am, for the moment, stuck context selecting to get the job done. Acck!! Phhht!!!

With OmniGraffle/7.2.2/GM-v176.7 update, the problem has disappeared. Case closed.