Nice bit of legalese in that circular logic which made Marshall famous.
The 10th Amendment didn’t need the word “expressly” to retain meaning and force anymore than it needed the phrase, “this means you”.
It declares that the powers ‘not delegated to the United States, nor prohibited to the states, are reserved to the states or to the people’, without equivocation, or condition.
Marshall was a traitor for imagining that one was needed.
Judging just by how you use the term 'traitor' I'd have to say that Chief Justice Marshall's understanding of the Constitution beats the hell out of your understanding of it.