His point is that there are no good non-Windows substitutes precisely because the non-Windows market for that software is too small and that by using the Windows version you are removing yourself from the already-too-small market that you should have been part of, which continues the cycle. Your points are definitely valid, but they only reinforce the argument that pirating Windows only harms the competition. Put another way, if you were completely unwilling to either pay for or pirate Windows, the market for the hypothetical non-Windows substitute for a program you need would is guaranteed to be one person larger than it currently is, whereas with the willingness to pirate Windows, that market may be one person smaller.