This fits in with their idea of approaching Lobo like Guillermo Del Toro did with the live-action Hellboy. If the actor is barely recognizable under heavy make-up and prosthetics, then you don't need a superstar -- you just need someone who can play the part. Clancy Brown can definitely play the part.
The Lobo comics are hyper-violent sci-fi comedies about an aggressively rude spacefaring mercenary. The upcoming movie finds Lobo landing on Earth in pursuit of fugitives, and dragging a human girl along with him to help him to acclimate to Earth. Clancy is no stranger to the DC Universe, having provided the distinctive voice of Lex Luthor to a large number of WB animated projects. Lobo is set to begin production in 2010.