^I don't know about elsewhere but here in Quebec, a farmer would have nothing to win by using human shit as a fertilizer. Animal farms produce so much feces that they don't know what to do with it. When spreading manure you can only fertilize a soil to some extend. Too much nitrate on a soil will actually lower its fertility. Agronomists can calculate the optimized quantity, but, here at least, farmers are often payed to use more manure then necessary, just to get rid of it.
Back to the main subject, I could see such a technology being used some very specific contexts. Like maybe a way to make the astronauts food last longer. If we wanna go on mars this could be a useful source of protein. Also, if you can safely extract protein from shit, we could just use it to feed livestock.