The reveal comes from X user @ChrisMack32, who posted a video showing them unplugging a Super Nintendo controller – connected via USB – at one of the...
Emulator projects should all add a clause in their EULA that specifically forbids Nintendo from using their software, then they can sue Nintendo for breaching their license. Give them a taste of their own medicine.
I personally don't think it's so likely that Nintendo would write and maintain a Windows emulator just for their museum if an open-source project exists that they could legally use for free under that project's license terms. Only someone with insider knowledge would be able to say for sure though.
That team writes emulators that run directly on Nintendo consoles, so they would likely test it on development versions of those consoles the same way actual console games are developed and tested. Otherwise they would be testing a Switch version of an SNES emulator running inside a Switch emulator on a Windows PC that would introduce it's own errors.