The state is abridging the right of a qualified registered to cast a vote of their choice. By declaring that person at the poll must provide documentation ( the unrequested mail-in-ballot and procedure for turn in ) the state is effectively stating their voter registration rolls are inaccurate and implementing a test or device to allow voting and requiring the ballot to be provisional.
The stste is violating their responisibilty to maintain accurate rolls if the qualified voter must vote a provional ballot.
(closest provisional ballot law found does not specically address the situation but the person meeting standards of a qualified registered voter should not be deemed a provisional voter by the state due to additional paperwork)
52 USC §21082. Provisional voting and voting information requirements
(a) Provisional voting requirements
If an individual declares that such individual is a registered voter in the jurisdiction in which the individual desires to vote and that the individual is eligible to vote in an election for Federal office, but the name of the individual does not appear on the official list of eligible voters for the polling place or an election official asserts that the individual is not eligible to vote, such individual shall be permitted to cast a provisional ballot as follows:
(1) An election official at the polling place shall notify the individual that the individual may cast a provisional ballot in that election.
(2) The individual shall be permitted to cast a provisional ballot at that polling place upon the execution of a written affirmation by the individual before an election official at the polling place stating that the individual is—
(A) a registered voter in the jurisdiction in which the individual desires to vote; and
(B) eligible to vote in that election.