Why is 'Ghost Rider' not listed in his filmography?

Probably because I don't believe he was in "Ghost Rider".

He is one of Wes Bentley's three ghouls.
Even James Franco can't do that voice :)

http://www.stooorage.com/show/1073/3940471_30-07.png

If you are referring to the ghoul who plays Abigor (Wind) in the movie, then the actor is Mathew Wilkinson. Though he does have a Michael Wincott feel about him.

http://www.imdb.com/media/rm2860620032/nm1187896