since it is simply an appeal to authority, proof is evidenced by the lack of citation provided
the majority judgement defines the constitutional limits of the taxing and spending clause. they do not reject the use of the commerce clause.
it does not define anything else; the constitutionality of other clauses is speculative inference, not decisive precedent
(if it did define anything else, you would be able to provide a citation of where this is defined, as this would be the exact place that legal scholars and future legislators would look)