It doesn't matter either way, in my opinion.
If Wal-Mart chooses not to sell 'hardcore rap' then all the hardcore rap fans can purchase from a third party. Columbia House still delivers to your mailbox and I get those shitty little membership things all the time, so I assume all the hardcore bangers get them as well.
If Wal-Mart chooses not to sell Maxim, Stuff, FHM and the like, so what? Publishers Clearing House offers subscriptions to these magazines and again, I get those friggin' things all the time. Plus you might win 1,000,000 dollars!!!!!!
It's sad that Wal-Mart wants to assume the right to push blanket moralism through it's chain of stores on the masses, but in the end Wal-Mart not selling me 'unedited records' and 'Men's' Magazines isn't the end of the world and it sure won't stop me from getting them if I so desire.