He's talking about playing non WinRT games in WinRT though. If you'd have to virtualize a DX9 game through DX11...I don't think that'd even work.
Well I think a developer can port their win32 DX9 game to a WinRT DX11.x game if they wanted to and sell it through the Windows Store. It'd be more work, I'm sure, so for now you see only ports of arcade type games that you also find on Steam and other phone stores. Still, MS should be more aggressive with it, they could be waiting to better unify the APIs with Windows Phone 8.1 first though.
With them allowing indies to get full access to use all of the Live services/features in their games for free then I also think they should extend that same policy to WP and Windows 8/RT games as well. Just let anyone who's already paying to have apps on the store be able to use Live in their games for no extra charge and red tape. Also, I see no reason why MS can't charge a small fee and have desktop games that use Live sold through the store directly as well. They let free desktop apps be listed for no charge but they should go right after the market and at least for full x86 Windows let the Store handle them. Developers would probably just have to repackage their games/apps.