Those regulations date back to before cannabis was legalized. In other words, the scientific aspect was not completely standardized.
Are we in a transition period? Do you expect that, at some point, when the science is more clearly established and the medical value of these products is certain, things will be standardized so the excise tax will not apply to products with a DIN, but will apply to all other products?
This is not the same situation as for non-prescription drugs.