It's not so weird. To them they are saving someone...from the article I posted: "We live in a world with hundreds of thousands of embryos frozen in the United States alone. Most who aren’t selected by their biological parents are donated to science or destroyed or kept frozen. If Christians – or others – really believe life begins at conception, it follows that we should respond by being willing to support embryo adoption and even take part in it ourselves." They both also wanted the wife to experience pregnancy which she couldn't do through a normal adoption
https://www.washingtonpost.com/news/acts-of-faith/wp/2016/04/21/my-wife-and-i-are-white-evangelicals-heres-why-we-chose-to-give-birth-to-black-triplets/?utm_term=.0cb18f724c9d