Well, in my personal experience, a man who is absolutely adamant before the baby is born can soften up after the birth. Seriously, what man is going to tell his post-partum wife, whom he just watched give birth to his perfect, miraculous baby, that she absolutely MUST do something to the child which will completely horrify and devastate her? That there absolutely MUST be more blood, gore, and tears?
When a circ'ed man is insisting on circ'ing his baby, what he is really searching for is affirmation. The idea that his wife might think that his penis isn't "right" is very threatening. So, IMO, it's important to avoind the "sex is better with a forekin" argument and just stick to the "medically unnecessary, avoidable trauma" (but you are perfect, honey) argument.
When I was gearing up to protect my ds#2, my husband was insistent that we circ. We never fight, but we fought about this. Eventually I got tired of the confrontation and just let it go, and then stood firm after the birth. There has never been a problem. DH has even come so far as to admit that he knows there's no benefit and that it takes away sensitivity.