Earlier quoted context omitted.
Because this would allow these millions of people to continue using this fork of XP rather than eventually buying a MS operating system.
But this is the attitude Microsoft needs to eliminate. The days of making money on operating systems is rapidly fading away. They already gave away Windows 8.1 as a free upgrade, so they're aware of it. An open source XP would get many hackers interested in Windows, something they desperately need.
They are definitely making money on closed-source operating systems and operating system tools:
http://www.microsoft.com/investor/EarningsAndFinancials/Earn...