but it seems like there are 2/3 threads being comingled in the case:

a) illegality of marijuana itself b) interstate commerce-related issues pertaining to private growth

the 'b' parts you mention definately seem like flawed, unconstitutional reasoning (e.g. expanding the definition of commercial and therefore regulated to include things that actually arent)

as for 'a' - "And when state legalizes it, all that means is that they're repealing state laws making it illegal."

this can't be true true - otherwise there would be no regulation/taxes on dispensaries, etc. in legalization states, which there certainly is..

so it's not like there is a federal law and a 'blank' at the state.. there are contradicting state laws treating it as legal, and federal ones which say it is illegal..