WGA Talks the Doc. Talk, But Lets Others Walk the Picket Line

Documentaries submitted for entry must contain an on-screen writing credit and have been exhibited theatrically in either New York or Los Angeles for one week in 2006.
The credited writers of these documentaries are required to join the WGAw’s Nonfiction Writers Caucus or WGAE Nonfiction Writers Committee in order to be considered.
Scripts need not be written under WGA jurisdiction.

So, while the writer needs to join a committee to be considered, the script could have been written under hell-hole working conditions, sub-par wages, and no benefits, no partipation and no residuals.