Did the UK? Cause it's from their law's that Barry got his UK citizenship, not Kenya's.
It looks like a Polygamy marriage in the US would not be illegal if the polygamist (Sr. in this case) was an Alien visitor. Which he was, and therefore apparently didn't break any US law.
Jihad Abdul cannot come to the US and marry 20 US citizens and all of those marriages be considered legal for immigration purposes.
Jihand Abdul can bring his 20 wives that he married in another country where it was legal and they will be considered his wives.
I cannot remember the exact law off the top of my head..so I did search to see if I could find the right law and found this site.
Look at the comments. There is a great discussion of applicable laws.
http://www.therightsideoflife.com/?p=4515