When I took SASS RO I, I specifically asked about the use of the "cavalry twist" and was informed that it was allowed but had to be safely and properly executed -which it can be with practice.
However, in my experience most ROs aren't comfortable with the cavalry draw so don't allow it, and don't even allow the shooter to demonstrate that he can do it correctly and safely. One RO once had me do the cross draw shuffle for both pistols - which totally screwed me up since I had the cavalry twist down cold and would automatically attempt to draw that way until I remembered I had to switch hands and swivel myself.
I know Tex favors a military impression from time to time, and he would be an invaluable supporter to those of us who like to shoot in uniform. Personally, I don't think we need a new SASS category per se as much as we need a better definition and label for the "Classic Cowboy" category so that it is more acceptable to those who want to accurately attire themselves as cowboys, soldiers, townsmen, or whatever. The GAF has established at their Musters that the cavalry twist can be done safely, so we should be able to contribute our practice experience to any SASS decision.
US Scout
GAF, Commanding