This design is devilishly clever, but a tad misleading. It's not really an HDMI display notwithstanding that it is a display that plugs into an HDMI port. HDMI has an embedded i2c bus, and this project uses that to send images to the display. That's why you need a layer of software (xrandr) to translate images that the system produces into i2c.
If you took the time to build this, then travelled back to the 1800's when people had standalone DVDs, and plugged this thing in expecting it to work, it would not kill my buzz: I'd find it quite entertaining to watch, really.