the kind of memory used is discussed in the case law defining copy for the purposes evaluating software under copyright law. obviously, unlike a book, software is copied from some manner of ROM to some manner of RAM to be used. As this is an essential step in the proper use of software it is not, as a matter of law, considered an unauthorized copying when in the course of legal use of software.
The basic argument in the case really isnt about the number of copies made. It strikes me as silly for apple to have even mentioned this, and from the linked article it is quite clear that this was taken somewhat out of context. The real technological issue as i read it is whether Pystar is modifying OS X or simply adding applications that allow it to be loaded. Pystar likens tinkering with the bootloader to adding Firefox or Word in place of Safari or TextEdit. It seems to me that code that determines how the OS is loaded is more properly classified as a part of the OS than a mere application. It is this modification of copyrighted code, not the copying of the modified OS X into RAM, that creates the unauthorized derivative work. From there, selling this modified OS X violates apple's right to create derivatives of its copyrighted work. the summary really takes 'unauthorized copy' out of context. copy of unauthorized derivative work is more accurate. If the version of OS X Pystar sells is found to be a derivative work rather than a pure copy, the "we purchase one copy of OS X per computer we sell, so it is all legitimate' defense falls flat.
So in this case, though i'm personally of the opinion that software is property not service, i'm more persuaded by apple's argument. Pystar is altering some of apple's code and then shipping it as if it is simply reselling it.
"The identical is equal to itself, since it is different." -- Franco Spisani