Hmmm. Should I address you as "they," or are you the aphorism fairy?
The reason his paradigm is being discounted, much like your own, is it fails to recognize the reactions are not commensurate to the offences. In fact, you seem to be studiously avoiding that point. This indicates to me the dynamic is not what he thinks it is.
One can take it at face value faithful moslems get to spend the rest of eternity whoring around with their own personal harem, or one can ask the more trenchant question "why is such behaviour permitted there, but prohibited here?".
Even if they are correct, this is no solution to the problem, because he cannot change her.
Wrong. I'm still married today because I was able to convince my wife she was judging me by my actions, and herself by her intentions. If this man does *nothing* you have a point. But my experience is that's seldom the case. More often, she has a script in her head, and he's suppose to follow it. The things he does usually aren't even on her script, so he gets no credit for them.
And that is all I'm advocating here. If this man shows his wife an impeccable example, she may be persuaded to change herself (if she is indeed a mere harpy running down his ego for her own ends). I doubt that this man will be able to persuade her verbally, as he is convinced that his shortcomings betray a lack of maturity that is so chronic that it prevents him from fulfilling even the most minor and simple everyday tasks; he will not be able to deal with her forthrightly, as an adult, because he doesn't think he has a leg to stand on.
In order to gain that leg, my advice to him is to do things that will instill self-discipline in order to mature. At that point he might have enough self-image to give him the confidence to deal with her as an adult male. Because, at present, he's acting like a child. This post is solid evidence of it.
A man who acts like a child cannot save his marriage, and saving his marriage is the man's stated aim. He must grow up. It will take discipline to do it. He can gain discipline if he follows the advice I've given him. (He can gain it in other ways as well, and some of those ways have been posted by others on this thread.)