He should make the argument, which is a good argument, that the children of parents who use their sexuality properly tend to be stronger and healthier than the children of parents who are dissolute, and have depleted themselves in the pursuit of the pleasures of the flesh.
It is the truth across the board, that people who waste themselves on empty sex, as well as smoking and drinking and gambling, drugs and other vices, have less of themselves and their spirit to lend to the upbringing of their children.
This does not mean that parents should not have fun or enjoy life, just that they should not do so in ways harmful to themselves or their children. Instead they should seek out activities that are both enjoyable and enrich the lives of their entire family.
Whilw we Evangelical Christians have our differences with the Catholic Church on how things are done, we are on the same page as they in matters like this.
Did you listen to his full homily prior to posting this? Your suggestion is an excellent one. Only yesterday, while shopping at the supermarket, I noticed two "women" pushing a cart with a young child on board (perhaps 2 years of age). One of the "women" sported a lengthy braid and chin whiskers. My heart went out to that child.