They're leapfrogging to a niche market of going from hardware to security on the Windows platform. What's the gain in getting into an specific platform's flaws (antivirus) and development environment? That's the corner of the platform itself, not to mention the scope of the OS industry.

If they want to do software, they should develop a OS, maybe for Atom or some kind of mobile platform or otherwise.

Antivirus is back and to the left.