> The GPL doesn't protect your right to run the modified code if the mere act of running modifying code is made illegal.
If you cannot comply with the terms of the GPL, you cannot distribute the GPL'd software at all. If the FCC prohibits you from distributing the tools and information necessary to build the source code as required by the GPL, then you have to stop using that software in your product. The FCC does not have the power to authorize copyright infringement like that.
You are correct, but that exemption is in the GPL itself so there's no issue. It's possible to ship GPLv3 code with locked down hardware if local law requires it.
If you cannot comply with the terms of the GPL, you cannot distribute the GPL'd software at all. If the FCC prohibits you from distributing the tools and information necessary to build the source code as required by the GPL, then you have to stop using that software in your product. The FCC does not have the power to authorize copyright infringement like that.