Again, I'm no lawyer, but from what I read about the Minor case, she was denied the right to vote, not because of her citizenship, but because she was female. This case goes back to the late 1800s, years before the right to vote was Constitutionally granted to women. The State of Missouri where Minor resided had a specific law barring women from voting. The Court decided that the state's law against women voting was valid since the US Constitution made no provision as to the right to vote to US citizens. The right was conferred by the states in their constitutions.
https://www.law.cornell.edu/supremecourt/text/88/162