Blackcloud6

I think you can move it to the data folder and rename it aaa so it will load before the default. The Z folder is there so it's the last thing it will load, but mods just need to be in the data folder. 
This won't work with uniform mods that have more variants than the stock game. 
But in the end it's best just to move it out of the game directory entirely. 

@Vacillator has it correct. The only other tactic you can use is tag the mod and use that tag in the scenario you want but that's really only good for scenario authors or people willing to crack open the scenario editor.

You can move it back out of the Z folder and store it somewhere else (I have transfer folders partly for doing this on my desktop).  It's a bit of a pain but not so bad for one or just a few mods.
I was going to suggest renaming it so that it loads first but the other version then loads later (the opposite of the zzzzz naming trick) but as you want the stock version it's not a mod, so that wouldn't work in this case.
There might be other suggestions, but moving it is a definite workaround.