First off, thanks for looking through Stars Go Cold. Your attention and criticism are of immeasurable value.
Second, Helicopter and Vectored Thrust units were considered for inclusion in SGC's unit listing, but their tactical niche was divided between ideas for off-board aerospace units and mechs. At present, I'm incorporating only 'boots on the ground' units but will playtest a VTOL unit type in the near future and see how they function.