Oh, it is VERY related! The case was NOT argued based on the Illegality of Marijauna, but whether the federal government had the power to regulate it under the commerce clause! This was the case where Scalia established the "one step away from interstate commerce" test.
The argument here is that by NOT engaging in commerce, you are adversely affecting the price others must pay (I know, oxymoron), thus under the powers "necessary and proper" to the commerce clause, the Federal government can oblige you to engage in said commerce.
Something that doesn't exist can't be transported.