It might have been something like with WW2 where women were recruited into traditionally male jobs with Rosie the Riveter propaganda posters etc, but when the war was over, they were pressured to give up their jobs. Probably something similar was going on with Truart and Karras lacking people for their organisations. I mean, Truart took in all sorts of people, including former criminals, and Karras didn't seem to be all that discriminating either. The former perhaps due to the Blackbrook war and the latter due to needing all the followers they could get. Probably also helped that Mechanists were oriented more on tinkering with technology than swinging an oversized hammer around.