Guess what, they finally posted the study:
http://www.atf.gov/publications/firearms/012611-study-on-importality-of-certain-shotguns.pdf
It discusses the importability of shotguns as it applies to the Gun Control act of 1968. I haven't read through it any thorough detail, but it appears that the Saiga is safe because it does not have any of the restricted features in its currently imported condition.