To slightly improve this:
- Download my attached Null Sample which has 0.001s of silence as a source.
- Reorder Null Sample to be first in the sample list.
- Relink all programs with intentionally unactivated synths to Null Sample. Most factory presets seemed to be linked to the first two string samples. You can bulk relink using sound manager.
- Now, all synth slots left deliberately empty or started from "Empty Program" will always show "Null Sample" as their sample. Bonus, if you have programs with unactivated synths that you plan to activate during play, you can just leave them alone to distinguish them from programs that don't use synth at all.
Not the most elegant solution, but figured I'd post about it in case it helps anyone else. Cheers!