There are threads on the XDA Developers Forums created by owners of WM6.x devices asking why they can't get WP7 working on their phone.
Here is one such thread, where the lack of a Snapdragon processor is cited as the main reason why it won't work on older devices.
So XDA is your source? <shaking head> I hope you source your academic work better than that.
While I have zero inside info as to such requirements... until you hear it from Microsoft explicitly, I'd be skeptical as to requiring a specific core that only comes from one company (Qualcomm)... while preventing Samsung (or others) from being able to
use their similar Hummingbird platform... not to mention variations of Tegra, i.MX or other Cortex based cores.