Are you aware of any other situation where an activity is legal by state law but illegal at the federal level? I don't understand why/how the USSC can let this stand.
It is indeed a strange situation.
So you react with righteous bull$hit indignation and call for totalitarian abuse. Absolutely typical.
"Are you aware of any other situation where an activity is legal by state law but illegal at the federal level? I don't understand why/how the USSC can let this stand."
One instance I can think of is possession of forearms by those who have been convicted of crimes. It is my understanding that under federal law people aren't supposed to be able to own firearms if they have been convicted of any crime involving violence, actual or threatened, regardless of whether the crime was a misdemeanor or felony. In my state and many others, it is only against the law to possess a firearm if you have been convicted of a felony. Local police will not arrest people for violating the federal law, only state law.
This is only one example I could think of off of the top of my head. No doubt there are many other examples of conduct legal under state law but illegal at the federal level.