For Roon, this does not matter, as we do not use the Apple services for discovering or speaking to Airplay devices. The same Airplay related code runs on Windows, Mac, and upcoming Linux builds.
@Rugby is right about the .NET thing… and just as @Skywatcher said, the code will perform slightly better on Windows than on Mac or Linux.
BootCamp has always left me with a bitter taste in my mouth… it generates too much heat, as the power management drivers never seem to be as good as they are on “true” Windows machines. I guess the Dells, HPs, and others actually write better drives for their primary OS than Apple does for a tack-on.
Your AS Rock mini is probably underpowered for Roon. It’ll run fine, but things will be slower than you could have it be.
This is a great thread about hardware, especially post 20 by @brian