I think he's preempting the Windows lock-in argument -- lots of people (including myself) are afraid to start projects using the MS tech stack because it's not

I think he's preempting the Windows lock-in argument -- lots of people (including myself) are afraid to start projects using the MS tech stack because it's not portable and doesn't play well with non-MS tech stacks. Mono is a solution that allows you to run your MS code on the unix-like stacks.