The relevance is that the guy who started that thread, Psychlist1972, is an actual Microsoft employee who works on a Microsoft team charged with everything in the thread title (including MIDI 2) and freely shares a lot of it on Gearspace. If Gearspace is new to you, it's where a lot of heavy hitters in the PC music world (Mac, too) congregate and provides way deeper immersion into PC nuts and bolts than we find on this site. There are undoubtedly more posts about MIDI 2 where Psychlist1972 also contributes but might be mixed in with other stuff. Search on his name or just cruise some of the really long-running threads on that Music and Computers forum and you'll come across it. I can't search around right this second, but I'll poke around in the next day or so and see if I can't find some more relevant MIDI 2 posts.
Also, I could be wrong, but I think the thread I linked to not only talks about ARM chips on laptops but they're coming for Windows desktops too.