No, it really IS that simple; she swore an oath to uphold the law. It is exactly her position as a government employee that obligates her to follow the law, not her own morality play.
Her rights are not being violated, nevermind those of ordinary citizens of all types, by expecting her to follow her oath on pain of dismissal.
She and her rights do not have superiority over anyone else's. This is the part the right wing nuts don't get; they do not have the right to force their morality on others! To allow otherwise is tyranny!
Either she does THE JOB, not her version of it, or she leaves. No constitutional violation anywhere in sight. If I hire a roofer, do I expect him to show up and decide to paint my house instead? ...and then tell me that I can't get my roof fixed in his county?
You're confusing a cynical play on your morals with civil rights. You're getting this one badly wrong and no amount of maneuvering is going to magically change the logical arguments presented.
Now stay the Fuck away from my civil rights, you moron - you're as dangerous as you are stupid because you'll happily throw them all away for a party trick.