This guy has a point, albeit founded upon shaky premises. Apple, as a company, possesses much more of a closed mentality than Microsoft in regards to how it relates to open source projects, at least as far as legally tying hardware to software is concerned.
However, I think it has already been pointed out in that post’s comment section that Apple contributes to, and uses, a number of open-source projects.
But I think that, while I find the premise of Apple being an "open-source enemy" to be presently and patently flawed, the company’s practices in regards to software do need to be assessed from an FOSS standpoint.
Apple makes use of a number of FOSS packages and contributes back to them. However, the company makes sure to use FOSS strategically, by only using FOSS packages that can boost Mac OS X from the ground up but gradually decreasing the usage of FOSS at the higher-level, more-visible layers of the operating system. One of the few visible FOSS components of OS X is the WebKit framework (used by Safari and Dashboard for web rendering), which is derived from several projects of the more Linux-friendly KDE.
Otherwise, Apple tries to use as many proprietary bits in OS X as possible; a prime issue (and one that even I’ve expressed concern about) is how X11-native applications, when ported to OS X’s (closed-source) pet API and toolkit, have to be derived as forks of the main branch of the application in order to "integrate" with the predominant look-and-feel of the operating system and GUI. Camino was derived from Firefox in this manner, as was Adium from Pidgin.
Even third-party closed-source programmers have to face this hurdle, as porting an application or application suite between Win32 and Cocoa (or Carbon) usually results in the distributors stating that they will not be able to deliver the next release of a software suite for one platform (usually, the one that goes lacking is OS X).
I particularly notice that, when an application has finally been rewritten for installation on OS X to fit in the user interface of OS X, the developers (and sometimes Apple) will state "such-and-such-app comes to the Mac."
Comes to the Mac? It was recoded for Aqua to Apple’s HUG, not brought to some obscure hardware platform!
And I think that is the answer: by keeping the toolkit closed-source and keeping the operating system (upon which the toolkit is dependent) tied exclusively to Apple’s Mac-branded hardware, Apple is attempting to give off that idea that an originally-cross-platform software application has been ported not just to a proprietary toolkit, but to an entirely-different hardware platform. It is a matter of image control, whereby Apple seeks to maintain and preserve this ideal image of a distinct and unique computing platform that is exclusive toward all other platforms. Even the transition from IBM’s PPC to Intel x86 didn’t dissipate or dent this image, as the maintenance of the hardware lock-in+toolkit dependency would ensure that anything for OS X would also be for "the Mac".
Personally, this would lead me to assume that Apple is a hardware company with a higher degree of exceptionalism for its own operating system and application software.
It reminds me of how Macromedia (now merged into Adobe Systems since 2005) was an application software company that had a higher degree of exceptionalism for its own webware and file formats.
The trouble of this approach is that, if another company with the same approach (in this case, Microsoft, an operating system company that had a higher degree of exceptionalism for its own application software, webware and file formats) and a larger size and budget to grow on, decides to edge into your market (.NET 3.0, with the much-touted Silverlight, XAML and other such graphic niceties), what are you to do? How do you react, and with whom should you ally? Macromedia, which already had Flex, Flash, AIR, MXML and other resources, was bought by long-time rival Adobe (which was previously touting SVG as a competitor to Flash prior to the acquisition), with a gradually-open (and open-source-friendly) approach being adopted by Adobe in order to compete for influence with Microsoft in the multimedia production arena.
Apple, however, doesn’t need fear any such competitive threat from Microsoft or Adobe. At present, no other desktop computing hardware distributor has such a high degree of exceptionalism for its own operating system and application software as does Apple.
Many in both the FOSS and Windows user communities view any higher degree of exceptionalism for a company’s own proprietary trimmings as "arrogance", "pomposity", "bigotry", "ignorance", "hypocrisy", etc. But any company, IMO, would take such an approach if they could afford losing potential sales opportunities; Adobe and Microsoft have historically taken such an approach towards their own stacks as well.
Plus, a higher exceptionalism for your own stack often results in loyal, high-paying customer bases, rumor communities and vigilant keyboard armies. Apple, Adobe and Microsoft all have such customer bases and fandoms, all of which are accused of being as shrill and arrogant as the companies to which they give such fealty, devotion and attention.
So a better question to ask of Apple would be this: "is Apple’s corporate exceptionalism a bigger open source enemy than Microsoft’s corporate exceptionalism?"
And my answer would be "Yes. Yes it is."