Originally Posted by SeriouslyLost

No. He's not likely to be paid in the US directly. His agent would be paid. He is merely acting for his employer (himself and/or agent and/or publishers), which may (or may not) have a consequent effect upon sales. A B1 visa would be easy to get and appropriate. Heck, a VWP for business would probably be broadly qualify as appropriate so long as he can guarantee that no one pays him for anything while in the US.