But you also have to follow the law when it specifies which goods and services licensed vendors will have to vend in order to keep their licenses, right?
This is not an argument, it's a tautology. What you're saying is, "If the law say x, the law says x." Duh. That's what the whole controversy is about: should the law revoke a professional license as a punishment for ethical behavior, e.g. for refusing to distribute a substance intended to injure or kill? And the answer is: no.
Let's see if this analogy helps: say there's a blind mom and dad who have an infant with normal eyesight. Say they strongly identify with the "blind community" and all the people they admire are blind. They come to the pharmacist with a prescription for ketoconazole which they mention they want to put in their baby's eyes to destroy his sight.
They have a prescription.
Ketoconazole is legal.
They're paying for it.
Do you sell it to them?
If you don't, should you lose your license?