Not being law-minded, I have no idea what this means.
“One man, one vote” destroys State sovereignty and is not required by the Federal constitution.
When Democrats win elections, they get to redistrict however they feel like it. When Republicans win elections, they get to redistrict however the Democrats feel like it.
“I have no idea what this means”
Here’s what it boils down to. Say there are three Congressional Districts each with a population of 100,000 people. In District 1 all residents are eligible to vote. In Districts 2 and 3 only 50% of residents are eligible to vote.
But since representation is set by total population and not eligible voter, all three get a Congressman.
As a result, the “votes” of the voters in Districts 2 and 3 count more than the voters of District 1.
What this case could do is toss out population as a factor, replacing it with number of eligible voters. The result would be that Districts 2 and 3 would be combined, making them equal to District 1.