Yes, it is a legitimate policy choice. In general, FedGov has sharply limited constitutional authority to force the states to carry out its wishes in the case of enforcing federal criminal laws. The precedent that comes to mind is Printz v. US, where SCOTUS struck down a FedGov law requiring that local police check the backgrounds of Americans who wanted to buy a firearm through a licensed dealer.
And obviously in the case of marijuana legalization, states like Colorado are already engaging in quasi-nullification: they're thumbing their nose at FedGov despite a federal law saying that mere possession of pot is a crime.
This is why FedGov tries to tie its mandates on states to funding, like speed limits and drinking ages. Remember Real ID was not a direct mandate on the states but a carrot-and-stick approach to nationalized drivers licenses (or, you could argue, a uniform national ID).
And obviously in the case of marijuana legalization, states like Colorado are already engaging in quasi-nullification: they're thumbing their nose at FedGov despite a federal law saying that mere possession of pot is a crime.
This is why FedGov tries to tie its mandates on states to funding, like speed limits and drinking ages. Remember Real ID was not a direct mandate on the states but a carrot-and-stick approach to nationalized drivers licenses (or, you could argue, a uniform national ID).