I'd say the flaw in his philosophy is that people could be trusted to be "loving authority" without being watched themselves, and do what was in the best interest of slaves they had power over. That's as much a fantasy as anything else in the comic. And it's just such an awful message to be sending to impressionable young readers, submit and give up independence and you'll be happy. Are there any Marston stories where Wonder Woman encourages someone to think for themselves, are we just getting all these posts about subjugation?
It reminds me so much of the ending of CS Lewis' THAT HIDEOUS STRENGTH where the Pendragon enlightens a young woman that her marriage has been troubled because she never seriously tried to "obey" as in her wedding vows.