An attacker swapping the monitor with one that records or displays other content isn't very different from the possibility that an attacker replaces your keyboard with one that keylogs or inserts crafted sequences of keypresses. I don't think ORWL tries to do anything about these possibilities, and it's difficult to imagine good fixes that don't massively change the scope of the project. And even if you do make the keyboard and monitor tamper-proofed and securely paired with the ORWL, it can't prevent an attacker from hiding a video camera in the room or using skimmer-like devices between the user and the devices.
