Any BIOS-based emulator is a copyright infringement as long as such BIOS isn't included on the download from GitHub.
We return to what I've said, the final user is the one that infringes the copyrights of the holders by the way they use such software, no emulator in existence (to my knowledge) is illegal.
If a final user decide to "create" the so called emulator AIO, and includes BIOS and ROM files from the systems it emulates, the developers of such emulators aren't responsible for any copyright infringement. Take as an example the very popular RetroArch, it is legal to use if you've made a dump of game cartridges you own.
I think Microsoft has a very clear idea of copyright infringement and that no emulator by the means of existence poses a threat to such copyrights, even those XBOX Emulators by themselves.
So then, no piracy has ever existed on GitHub.