If you think MS-focussed people are generally low-skill and uninterested, it will be difficult to hire them for a non-MS skill (or any skill, for that matter).

If you think MS-focussed people are generally low-skill and uninterested, it will be difficult to hire them for a non-MS skill (or any skill, for that matter). But that can apply generally. Need C# but they only know Java? Cancel. I'm fine with canceling people who are lazy or not smart or not interested, but canceling someone because of their stack just seems like finding plausible deniability.