"Open Source Developer" is not a job or career or profession. How many people out there really make their money checking in open source code? 0.1% of all developers? 0.01%? Most people do it in their free time, use it as marketing tool for their consulting/commercial offers, etc.

Miguel de Icaza for one might have Macbook, but I am sure it at least dual boots to Windows. It would not be possible otherwise, since he needs to run .NET non-stop and copy/paste code from Reflector to his Mono implementation, or whatever they are doing to clone .NET to Mono.

And I am pretty sure Apple Software has nothing to do with how they really win their bucks. So no need to look for logic here - they just like the shiny hardware cause they are geeks. That's it. No rocket science or philosophy here.