Because they received direct monetary compensation from it.
Seriously, that's like Bond villain levels. Megaupload host all of those illegal pirate copies of music that hurt the music industry and the person who runs it is... from the music industry?! I don't doubt those laundring and conspiracy charges at all. After the music industry, the one the CEO is from, is harmed from the pirating practices he'd have the last laugh getting all the profits from the illegal trade.
The seven suspects have been charged with participating in a racketeering conspiracy, conspiring to commit copyright infringement, conspiring to commit money laundering and two substantive counts of criminal copyright infringement. source:
http://abcnews.go.com/Technology/justice-fbi-crack-megaupload/story?id=15396526#.TxidwPnNlGU
Makes a lot of sense to promote the very thing you're the CEO of.