I'm not a lawyer, but it seems to me that the odds of winning any kind of defamation or slander suit related to comments made on a website like this are very slim. I'd be interested to see if there is any previous case history related to this. Multiply the dismal odds of success by the limited assets of the people who would be sued, and you've got a case no lawyer would touch. Unless, that is, somebody were paying him to go ahead with the suit for other, nonmonetary reasons.
The IRS has first dibs on the sweat on my rump.