Well, the advice I gave was for a wife who attempts to both withhold sex and forbid porn. So of course, if the wife refuses to be sexual I would advise the husband to flaunt the use of porn and tell the wife that she holds the key to ending it f she finds porn and masturbation distasteful. Most likely saying this will not make a wife more sexual toward the husband, but it's really senseless to accept the thought that porn should be forbidden in sexless marriage (to add insult to injury).
In fairness to you, this approach DOES work in some circumstances. This is kind of how the Army gets people to go on through upleasant stuff - that the key to getting past it is in their hands and down to their effort. It works well with people who WANT to succeed. I agree though that in general it isn't going to make someone not motivated to improve get that motivation. It's more likely to have the opposite effect. But then, I guess you KNOW where you are then, don't you?
Regarding your statement of benefit, if she sees no benefit to being a sexual wife, that is the husband's failure. The benefit being the fullness, richness and pleasure of her married life and family being at stake. Husband needs to provide all of this, and make it so that she would fight hard to keep it.
If she's getting every bit of fullness, richness and pleasure she wants without sex, why would she bother? The husband is trying to sell ice to eskimos.
Which is why I advised the OP to run with a thought of how to keep his wife sexual, and not run with a thought of allowing his sex life to crumble and then be in a mode where he is stuck with bills, kids, pets etch.
"Keep" implies "already is, can be maintained". If it's already cold and dead? I wonder how much manning up can help in these cases. If a man's wife's sexuality is like a broken down car, if it conked a short time ago, I buy it will work. But with some of the cases here it sounds like the scrap cars I used to see at my granpa's house, that had been there so long there were trees growing through the roof - how do you get THEM running again?