I take it that in this case you mean the codebase as UNIX. And it's MUCH more complex than you portray it. Also don't forget that the current SCO was formerly named Caldera, which was working with IBM, HP, SGI and others on the successful Project Trillian to get Linux running on the IA-64 platform. Going from your point of view. I'd say SCO was trying to destroy UNIX too, along with another company you think was ruined by Linux, SGI.
Apple saw the threat to their business (of cheap Linux on Intel clones with similar GUI's) and quickly dropped IBM processors and switched to Intel to combat both
Apple dropped IBM and Motorola/Freescale because they couldn't keep the PowerPC processors competitive with the x86 world. Part of this was simple economy of scale: Apple didn't have enough demand to justify the R&D to keep a lead in desktop processor technology.
Apple is using BSD because Jobs created NeXT and that system used BSD, and he decided to base OS X on NeXT after he took over Apple.
Too bad for them, Long Live UNIX.
UNIX as trademark? Doesn't apply to OpenSolaris. UNIX as UNIX functionality? Linux is pretty much an equal. UNIX as codebase? Doesn't apply to most of them.
The NeXT systems were by far the nicest workstation or desktop computers I had ever seen. They were better than Windows 95 systems about 5 years before Windows 95. The problem was distribution, the same problem Apple has today. There's just not enough good to go around in this world, sometimes, as a Linux box with an OSX skin is nowhere near the same O/S.
Minor nitpick. After a couple of failed attempts to create a next-generation OS, Apple had already decided to build on NextStep when they bought NeXT. Bringing back Steve was a bonus. At the time, it wasn't announced that Jobs would be back as CEO, but I think everyone involved in the deal pretty much knew the score and just forgot to tell Gil Amelio.