Have you ever listened to his talks? I have read a bunch of what he has written (mostly transcripts of talks) and did not get that impression. His main point is not that you are a "bad person" for using proprietary software--rather, it's more like you are the victim. Now, he does believe you should not use proprietary software, but because it's abusive and takes away your rights. Finally, I could see getting the impression that people publishing proprietary software are "bad", but that's a different story altogether.

Also, we're mostly developers here. Barring a few fields (things like .NET and iOS), free software is the best option for development. So while an artist using exclusively free software may be making a sacrifice, I have actually been much more productive on Linux/Emacs than I ever was on OS X or Windows. It's really a win-win situation.