I could be wrong, but I don't think the decision would have extended to the actual voting rights. At least directly.
Like they wouldn't be able to make a law saying that black people can't vote; after all, it's only "time, places and manner", which in no way includes who. But they could make it much, much harder for specific groups of people to vote.
I believe the post above yours is missing a semicolon or perhaps a clarification, so it should read something like: