People tend to build their identities around their affiliation. Attacking Apple probably makes him feel like you are attacking him. Similarly his support of Apple is merely him supporting his own identity. It's silly, I know, but people do that all the time. It's freakishly hard for people caught in the identity/affiliation trap to disentangle that aspect of their psyche's.
It's often why you can observe fantastic levels of cognitive dissonance in people over politics or religion or other things that people build affiliation around...it's simply easier to think inconsistently than to untangle one's own identity. Rational evaluation simply goes out the window since identity is primal, emotional.
Apple is the best in the world at building the link between identity and affiliation. They don't just sell stuff, they sell an identity. Being an Apple fan is being one of the cool kids, it's part of the "in" crowd, it keeps you from being a boring accountant looking guy in a suit, it's hip, it goes against "the man", etc. All of these are what Apple's advertisements sell, not their stuff. Apple's advertisements don't just list off features and talk about why they are better, they show cool looking people dancing in silhouette, or hip young dudes looking disdainfully on a suit wearing PC user, or a colorful Olympic athlete throwing hammers at gray talking heads, etc. etc. etc.
"Buying Apple makes you cool"
http://upload.wikimedia.org/wikipedia/en/a/ab/Imamacimapc.jp...
"Buying Apple makes you stand out in a crowd"
http://www.iphonefootprint.com/wp-content/uploads/2009/05/ma...
"Buying Apple makes you an olympian"
http://www.sptimes.com/2007/02/04/images/apple-1984.jpg
"Buying Apple makes you an artist"
http://top-technology-reviews.com/uploadfiles/top-technology...
"Buying Apple makes you a great dancer"
http://adstrategy.files.wordpress.com/2010/03/apple.jpg
"Buying Apple makes you smart like Einstein"
http://ivovodanovic.cl/wp-content/uploads/2009/09/old-apple-...
"Buying Apple makes you a leader among men"
http://adhdrollercoaster.org/wp-content/uploads/2009/01/appl...
etc. etc. etc.
Pick a positive trait, things that people want to be and Apple has probably run an ad campaign around it. It's why people line up around the block to buy a new Apple product sight unseen. They need to show their affiliation with the club of Apple.
Apple doesn't advertise cute, or quirky, or super technical, they advertise the kind of person that people want to be. They advertise the quarterback in HS or the head cheerleader. They advertise Martin Luther King JR. and Einstein. They advertise the philosophical cool guy with the vintage yet cool outfit that hangs around coffee shops and debates French literature. They don't advertise the nerdy guy in his parent's basement, or the D&D geek. They don't advertise the quiet genius, toiling away on hard and esoteric problems for years on end, they advertise leaders! They don't even really advertise "ease of use", "great price", "best specs". They advertise a coherent image.
And then, to close the deal? They actually provide a pretty nice piece of hardware and some pretty decent software that's well integrated, well thought out and generally easy to use. This justifies the entire image building exercise.
So the moral to my story is that, don't get frustrated with people who appear to have useless blind allegiance to the cult of Apple. What you are asking them to do is to be objectively critical of themselves, which to be honest, almost no one is able to do.
(full disclosure, I have plenty of areas where I have this problem myself, I guess it's just basic human nature)