No contradiction

"How can you don't have to worry about the viruses and spyware that PCs do and it did not claim Macs were entirely immune to viruses be both true? Either Macs are entirely immune or appropriate precautions should be taken to avoid them."

Easy. It is an easy enough to prove empirical fact that currently there are basically NO viruses out there in the wild for Mac OS X. None, whatsoever (apart from a few academic proof of concepts that you have to consciously download and try out if you really want to). Does that mean there are definitely no vulnerabilities in Mac OS X that could be exploited in future? No, of course not, no one is claiming that, just that there aren't any which are being actively exploited now.

Although I'm very happy with my Mac, like many others I also find the smug attitude of some Mac users quite annoying. I'm sure there are plenty of virus writers who would love to take Apple down a peg or two, so I can't believe that the current lack of attacks is purely down to market share.