Earlier quoted context omitted.
I've wondered the same. Here's some educated guesswork & rumour mongering: They're known to use "Teradata" (i.e. Dell), "Oracle" (i.e. FKA Sun) & HP DL-series servers alongside NetApp storage. iTunes is reportedly one of the world's largest SAP installations and that'll almost certainly be on AIX or Solaris with Oracle databases on the aforementioned NetApp spindles. OS for other applications? Nothing stops Apple run…
I used to think that buying SUN would have been a smart move for Apple. SUN were pretty much the Apple of enterprise, propriety OS, CPUs, hardware, software. While there was little user synergy, the $5.6 Bn Oracle payed now seems cheap for the access to SUN's IP & patents. They had a talented CPU and OS design team and expertise in building data centers, which Apple is now catching up with.
Even if what you said were true, I don't know how it would be relevant. Darwin, which OS X is built upon is open source as well. Apple contributes to FreeBSD and it gave us clang. Hardly an example of a company that embraces closed source.
SPARC was interesting from a technical standpoint, but it wouldn't have been an asset to Apple. SPARC doesn't shine on low-end machines and they already had to ditch twice fancy CPU architectures. Internal servers? Hardly worth keeping a CPU division for when AMD64 works just fine.