O motivo pode ser encontrado no documento TempleOS Por que não mais
I don't stand a chance working on native hardware, anymore. I could install and run natively on hardware from about 2005-2010. It requires BIOS's being nice enough to write USB mode PS/2 legacy keyboard/mouse support. As it turns-out, sometimes the BIOS has PS/2 drivers but purposely disables them, just to be mean. The CIA and whole industry is trying to mess everything up, on purpose. Perhaps, at a point of sale in a store, a thief could hack a credit card machine. Therefore, the BIOS companies actually want it difficult to make drivers and purposely make it broken.
Parece que o TempleOS requer emulação PS / 2 para dispositivos USB, ou um mouse e teclado PS / 2, e é isso que Terry também está se referindo.