The best I can find is the following. It is very possible that I have missed something.
Page 11 SHB
*Shooting categories offered at any match are ultimately at the discretion of the Match Officials to ensure the success and viability of each match individually unless the individual contract indicates otherwise.
From the 2026 SASS Championship Sanctioning Match Contracts
Event Requirements
• Conduct match in accordance with SASS Rules, and within the outline of the guidelines provided
So, unless the SASS contract specifically states otherwise, there are no protected categories, the match director has the final say.