True, but contractors are "scored" as to how well they have substituted from the bad list of chemicals to the "pc" list of chemicals. Many companies have management edicts to make that changeover 100%, since the environmental weenies claim that the substitutes are just as good as what they replace.
On the surface of this, it means that the path of least reisitance is to make the change and reconsider only if something goes wrong. This is what was happening in LM and LM was in charge of the fuel tank. It would be a career limiting move for a materials engineer to apply to use the exemption.
Bingo! NASA "Award Fees" determine whether the contractor makes a profit that year or not.