Actually it's pretty simple. You didn't "buy" OSX, you bought a license to use it under certain circumstances, but Apple still owns it. If you decide to access it, in a manner that Apple doesn't approve of, you're hacking their property, not modding your own.
Don't forget that all licenses and contracts are subject to the restrictions of law. Terms can, and have been, found unenforceable.
Yes, I understand their license agreement, but I still don't agree with it.
It doesn't sound like it passes "fair use" laws and such.