Although MS' stance to block old vulnerable grub installs seems reasonable here, I've come to run Windows only for games and a single piece of legacy software (as a backup for my aging x86 Mac) without net access at all. The moment you allow Win updates, everything is up to chances. MS moving around registry keys and other shenanigans to force "telemetry" (aka ads and behavioral data scanning for ML) onto users, even on Windows Pro, should be telling enough. Needless to say, I'm running Win 10.