Without rebar, I am concerned with how well these structures hold up against earthquakes. There are places where earthquakes are not a significant consideration, but it is probably something that limits where this sort of tech could be deployed.

Maybe there are alternative ways of increasing the tensile strength of the material that lend themselves to this sort of manufacturing. Incorporating some sort of fibrous material into the mix maybe?

Right. The article refers to the fact that it may be of use to China's poor.

3-d printed outhouse. boom, problem solved

They're just ahead of the curve, a century from now people will be amazed that 20th century first-worlders went to so much expense and effort to bring filth and vermin as close as possible to where they live.

Water isn't cleaning the fecal bacteria off the toothbrush you keep in the same room as your toilet, your wall-to-wall carpeting is full of food crumbs that roaches love, etc.