That's valid, but the thrust of the top-level comment is that the computers are infected because they were windows (sounds plausible) with the implication that

That's valid, but the thrust of the top-level comment is that the computers are infected because they were windows (sounds plausible) with the implication that if windows were not the dominant desktop OS, malware would not exist (which is improbable). Malware is only rare for MacOS and Linux because those are niche OSes, not because of inherently higher resistance.