I believe when we originally discussed rules for this game, we settled on allowing commercial bases on the logic that we’re not banning naturals for being complex materials, and some bases act as substitutes for expensive naturals that are out of reach for some perfumers.
That said, for my entry I’m planning on disclosing all ingredients used, so the judges will know if I used bases. I’m hoping to avoid that (just for the extra challenge), but one blend I’m working on uses a base to replicate a natural musk I’d rather avoid.