So my dirty solution works, or at least works enough. I set the ability scores to 1 (-9 in the race tab of the editor). I determined the validation for zero scores runs at Validation phase 10000. Because the scores are 1, that validation error doesn't report. Then I added an eval script at Validation phase 11000:
Code:
hero.childfound[aINT].field[aFinalVal].value -= 1
Replace aINT with whatever score you want reduced to zero.
Fortunately, both 1 and 0 ability scores grant a -5 bonus to skills and such that use those scores. But I'm sure there might be edge cases where it being 1 (instead of 0) will break something. But at least with all the vehicles and objects I'll be using this for, it doesn't hurt anything.