Not true.
In this case, the state will be actively promoting it, by licensing growers and retailers.
That’s about as “legal” as it gets.
What are the Feds gonna do? Invade the state?
No state of the United States can actively permit something that the federal government has forbidden. It will be challenged in the courts and it will be struck down.
The feds will arrest and prosecute sellers. That's what it does now. The state can't provide immunity against a federal crime, and no state has offered to pay for the legal defense of somebody charged by the feds.
Not saying it's right or moral, just noting that all power flows from the barrel of a gun, and the feds have superior firepower, and the will to use it.