Who knows if the "deleted" data can still be sold off. Sure you can't view it on the website, but nobody knows what Reddit will hand to Google. Then again certain laws passed recently might make such a thing illegal...
The second option I linked also replaces all comments and posts with random scrambled gibberish, not only "deleting" it. I would agree that deleted != actually deleted, but scrambling all content might actually work to prevent further siphoning
