That's called a baseband processor.

But no, in all seriousness, Copperhead (and AOSP itself) are open source. Go audit it for NSA backdoors yourself if you're worried about that.

Do you mean, "this is a honeypot put out by the NSA, to see who wants this"? Or do you mean, "this is an attempt by the developers to see how the NSA tries to subvert, sabotage, or otherwise compromise their project"?

I know a guy who works on this. It's definitely not (not that you have any reason to trust me).

What makes you say that?