The main idea is that Congress can decide if it is legal or not, but to say it's illegal everywhere except for Nevada makes it a non-federal statute as they are arbitrarily deciding that some state gets an exception, making it non constitutional.
That is why it was stricken. If it said it was illegal everywhere, then the supreme court would have upheld that.
That is why it was stricken. If it said it was illegal everywhere, then the supreme court would have upheld that.