In Heaven wrote:
"The Times, Places and Manner of holding Elections for Senators and Representatives, shall be prescribed in each State by the Legislature thereof; but the Congress may at any time by Law make or alter such Regulations, except as to the Places of chusing Senators."
Your point is well-taken. But...
One of the "Regulations" regarding voting passed by Congress is called The Voting Rights Act.
Another was the 14th Amendment, which guarantees everyone "due process under law".
The law that created IRV in Maine violates both the spirit and the letter of both of the above, in my opinion.
It took the 2nd place finisher and made him the winner of the election, even though the candidate he "defeated" received MORE votes cast.
If such a law had been used in the old south to prevent black candidates from winning, how would that have gone over?