I never did understand how Apple can restrict MacOS to only Mac-branded computers. You should be able to use software on any hardware you want. You already paid Apple for the software, you just don't want to use their hardware.
This is where most people get confused. Apple doesn't sell a separate OS. They sell a fully integrated product, their Macintosh line of computers. The computer and the operating system make up one single product, not two separate products. There are many examples of this on the market; Playstation, XBox, Blackberry, Palm, iPad, etc... These are all devices that run their own OS and that OS only runs on those devices, computers aren't any different. The only difference is user attitude; people are used to Microsoft's business model of providing and selling the OS and letting people install it on any compatible computer. People forget there was a time when there were many computers on the market that ran their own OS; Tandy, Amiga, Atari... Apple is the last of these companies.
Also Apple makes Mac OS
UPGRADES available to people who already own Macintosh computers. The only reason there is a retail box of Mac OS X is because it was far more convenient for most Mac users to make a quick trip to the store and buy the DVD, than to download an entire OS.
...Thats how absurd it is that Apple can tell you on what machine you can use a software.
It's not absurd for Apple to tell you how they want their product used. Most products come with disclaimers and a warranty telling you how the product should be used. If you fail to use the product in accordance to these, then the company absolves themselves from liability and the warranty is voided.
Second, Apple doesn't care if YOU want to install OS X on non-Macintosh hardware. (There is a thriving hackintosh community.) However Apple will not support the OS running on that hardware after you violate the EULA.
Copyright laws are there to protect the IP rights of companies by clearly defining their rights and limitations. They are not there to protect the pockets of corporations by allowing them abuse their rights and infringe on your rights.
How exactly is Apple abusing its rights as a corporation?
And how exactly are they infringing on your rights as a consumer?
Sorry, but you do not have a right to buy and own Mac OS X. Apple only makes their product available to you by agreeing to their fair terms of use (EULA). It would be different if Apple was the only company that developed a computer operating system, but that's the case here. You have many other alternatives to choose from to support your hardware, whatever that may be.