$500 to be a whore. No.
What Samsung asked him to do is way worse than prostitution.
Assuming these posts would be moderated fairly quickly and thus not have that much impact on the site, would it not be worth posting one of these if it means a $1k donation to stackoverflow.com? How about 10k?
Surely at some point the benefits outweigh the damage.
$2 is about right (http://www.thepricegeek.com/results/my+integrity?country=us)