Obviously you need to be pretty paranoid to believe that the NSA has corrupted the GNU toolchain in such a way that it inserts back doors in every OS kernel it compiles, that the debugger has code inserted in it to not display said OS code, etc, but it is technically possible.
If there was only one program that could display object files, it could be done. But any number of programs can display object files, including plain hex editors. If every single hex editor would have been compromised, we would have noticed by now. And a compiler that can detect "oh, this code is a hex editor, I'd better patch it to make it hide the nasty stuff when it's run" is way beyond what can currently be created, certainly not running fast enough on an ordinary PC to avoid detection.
Besides, it's not the question of whether the NSA can access your files if they consider it their highest priority. The problem is that if there is an easy, low-cost way to access your files, an individual rogue agent might do it and hand your files to your competitor (a favor for a friend or for a little extra cash) without the rest of the NSA even knowing about it, or finding out only after the fact.