DP doesn't give a stuff about illegal sales - they don't police what others choose to sell. Selling an eBook about warez doesn't exactly constitute a crime anyway. I bet the infraction/warning was because the thread was either bumped or in the wrong place. Edit: Having looked at the thread in question it's also possible it was mistaken for an invitation/account sale, which is now prohibited around here.
Its better to try and sale those things on warez forums or something as DP wouldn't want to get in trouble for those sales.