The Supreme Court also said at paragraph 65, and they used an example of applying proper procedure to a situation:
However, unlike the rejection of a valid vote, turning away a voter on election day is not fatal to that person’s right to vote.
Then they do the flip side of that, which is if a vote cast by an entitled voter were to be rejected, they would be permanently disenfranchised. The court seems to recognize that reasonable compliance procedures, like asking for identification, are acceptable.