Curveman,
I understand where you're coming from. We've certainly seen the boundries of what constitutes a "longbow" expanded quite a bit in the past few years.
According to some definitions, a Hoyt FITA riser (Aerotech, whatever) with a plunger, elevated rest, short stabilizer and ILF longbow limbs would be considered a longbow. In other instances, the bow must be shot off the shelf, no stabilizers, and have a D shape when braced.
Personally, to me what does or does not constitute a longbow is only relevant if you're in a particular venue that has a set definition (IBO, IFAA, etc.). In that case, it comes down to any other such equipment rule: follow it or go elsewhere. Aside from that, I think it's really irrelevant.