The Lexmark case is really difficult to apply, because in that question the only purpose of the software in question was to restrict access; it served no purpose but to activate the hardware. That was the basis of the judgement: since the software was necessary to make the cartridge function, it was not copyrightable and duplicating it was not a "circumvention." Since there are other ways to make Pystar's hardware functional (eg. install Windows or Linux on it) that argument doesn't apply in this case.
Likewise, once you buy a disc containing OS X, you have access to all the code stored on that disc. The access control is your purchase of the disc, not the interaction between the disc an an Apple-branded computer.
Which is all well and good for the boxed copy that Pystar ships, but not for the cracked copy that they preinstall. Legally, the included shrink-wrapped copy and the on-disk cracked copy are two separate issues.