1 - You are being inflammatory and immature. You are welcome to raise your own opinions without questioning the testicular fortitude of everyone on this site.
2 - Pixelmator is reliant on ImageMagick, which is governed by the ImageMagick license. This license in no way prohibits commercial use of the library, and requires only attribution. By all accounts Pixelmator has respected this license.
3 - Not only has Pixelmator respected the letter of the license agreement, but it even widely advertises its use of open source components. How this is a bad thing for open source in general, only you seem to know.
4 - To pre-empt any Stallman-esque tirades about the evils of commercial exploitation of open source software... remember that no developers are in any way forced to allow others to commercial exploit their open source work. ImageMagick has done this out of their own accord, and it would be presumptuous to assume that people following their license are exploiting them in a way they did not intend. Furthermore, from what I can tell Pixelmator has added extremely substantial functionality to ImageMagick (a top-end GUI app instead of a command-line app, really?), and is deserving of whatever commercial success they may derive from this work.
Oh, you think these comments are supposed to be generated using your testicles! That's your problem right there. See, most of us use our eyes, brains and fingers. Commenting with your testicles sounds awkward and painful. I'm sorry you've had to go through that.
Can Pixelmator to do unto others?