For a given piece of work, holding the copyright means owning the work. A license is a set of conditions through which owners let non-owners or a subset of them access and use the work.
The license doesn't apply to the copyright holder, because he owns the work. He doesn't need permission to use it (=> doesn't access the work through any license). He doesn't need permission either to let anybody use it in any given way he chooses.
The GPL only applies to GPL-licensed code, there is nothing to interpret there.