It doesn't matter what they bought. Both are upgrade licenses. Hackintosh usages do not involve any actual upgrading whatsoever.
No, they are NOT upgrade licenses. My EUR 29 Snow Leopard box has this printed on it:
"MAC OSX V10.6 RETAIL (1P) Part No. MC223D/A."
Repeat: It has a RETAIL label on it.
It says NOWHERE on the box -or- the EULA that you need to own a previous version. It does not even say that you are only allowed to use this on a Mac on the box. Only in the system requirements it says "Mac-Computer with Intel CPU." But that's nothing else than saying that you need an Intel CPU to run Windows, even though it actually also runs on an AMD processor (which is compatible with the Intel product).
And then, when I open the Snow Leopard RETAIL box, I magically find no printed license agreement in it.
And the sum of this, in German - and most likely in all European - legal terms, simply means that Apple's license terms are NULL and VOID and not binding at all.
Or let me ask you folks this question: If Sony was selling BluRay discs that could only be played on Sony's own BluRay players, would you honestly try to tell me that this was legal?
I know that most American folks will now say yes, but you know what? That is only because you have gotten too used to your completely absurd legal system.
And a few words about the wide-spread myth that Apple is a hardware company and that their OS prices are based upon a bundling strategy: Apple's OS is largely based upon Open Source technoligies - namely FreeBSD - and that means that have much lower software development costs than their largest competitor named Microsoft. Furthermore, a Microsoft Systembuilder licenses begins at around 70 Euros for an end user - and large OEMs get the SAME software much cheaper than that. Since Apple does not sell their software packages with included support, their product is not much different from those Systembuilder/OEM packages, which are software without any service, support or warranty.
Now Leopard did cost EUR 129 when it was released, which is around the level of Windows Vista Professional or Windows 7 Professional. When that price is profitable for Microsoft, it most certainly also is profitable for Apple. Because, you know, Apple is in the hardware business and thus they usually "give away" their software with the hardware bundle. That means that selling upgrade or retail boxes of software is just a bonus business for them...