He never said anything about the plant being feminized and feminized plants are notorious for going hermie so many experienced growers won't grow them. I never have.
If you get seed(s) from a bud grown from a feminized plant then it grew balls somewhere so you tell me where the male chromosome came from. I'm a chemist, not a geneticist.
I just know the basics of how genes work. To get into stabilizing a strain I'd have to have a good manual at hand and refer to it often to stay on the right track. Fun to do some pollen chucking and see what you get from various crosses tho.