Some developers adapt to OSX, but, if you read TFA, you'll realize this is not a cross section of the hard-core hacker types: 80% of the sample prefers Windows.
OSX is quite acceptable in roles traditionally reserved to Windows PCs in the corporate world. It runs Office, Outlook, talks nicely to Exchange and runs Eclipse just fine. Many corporate Java developers (a bunch that traditionally used Windows) can use Macs for work and enjoy some advantages in relation to those who use Windows.
You may argue that Linux is not as polished a Unix as OSX (I disagree, but smart people believe it), but no serious hacker thinks Windows is acceptable for development unless they are also targeting Windows for deployment.