This is a holy-sh** moment for me, suddenly finding out where Grant may have found his inspiration!

As for the short stem extension favoring stem shifters, Schwinn seems to be the first to have made shifter mounts that positioned the shift levers ahead of the stem quill axis (Suntour later offered long stem shift levers with brackets for either ahead of or behind the stem quill axis).

The forward-offset Twin-Stik levers are the bomb for use with a racing-length stem: