This is something no on discusses but I've wondered heavily- GRUB can be made to not show a menu and then boot up Windows automatically, in like a second or two with no one the wiser. [There is an obnoxious welcome to grub message that pops up now but I see a public project out there that solves this very easily called GRUB shusher]

I don't know if other bootloaders outside GRUB have a silent/hidden start option, as well in a similar vein that would require you to hit a key in that first second to get the menu to appear, or else it just boots up normally

I wonder about the other approach, just going into the BIOS nad changing the order so Windows boots first, which should be doable in some setups. Lock the BIOS with a password, and you're in not bad shape. (Not sure if Secure Boot being enabled could also help here - probably couldn't hurt)