Yes, the Sig 556, Sig SG556, or whatever you would like to call it is made for Cybergun by CYMA and legally trademarked with Sig trades on the body, stock, and magazines.
People are correct in saying that Cybergun does not actually produce any of its airsoft. They do have it made by JG, CYMA, D-Boys, A&K, AGM, and a few others and then legally trademarks as they own the rights to about 24 different trademarks worldwide.
As for Section 8, I spoken with the owner several times and corresponded with him via email. They do not get in large quantities of anything at one time, and they do not import any black airsoft on their own. All of the black airsoft guns they get come from a source in Canada that imports them. As long as they have the model in stock that you want, you will get it provided you are 18+.