2 options here.
1. Move the cockpit door to include the forward toilet in the Flightdeck. Or have doors to secure the forward galley and have only crew members use the forward toilet.
2. But the 2 crewmembers on Flightdeck at all times is a good policy. My Company has the same policy and we are in the Far East. It was the MH370 loss that stimulated that change for us. Some companies in Europe and now in Asia, have adopted this policy. My thinking is though an ICAO directive or recommendation should be inplace. Then individual states should enforce adoption of such a policy. Even it being already inforce through the FAA. Also Insurance companies should be pushing for this policy aswell.