That's a pretty useless article, frankly. They didn't even say what new policy is. I had to turn to DesNews
https://www.deseretnews.com/article...on-families-in-same-sex-marriages.html?pg=all
So the policy is that they must be adults, and must affirm the church's position on homosexual relationships, before they can join the church.
The "affirm the church's position" part isn't particularly shocking to me. And in a sense it's not a new policy at all because people are routinely asked if they support church leaders as one of the interview questions prior to baptism/priesthood/mission/etc. The church is just clarifying one specific case in which the positions of church leaders must be supported.
The bit about having to wait until legal age does surprise me a bit, but seems not unreasonable to me that if a child is under the care of someone who is blatantly opposed to one of the core LDS teachings, the church would want to wait until the child is living on his/her own before asking the individual if they support the church's teachings in this. Otherwise it might put the individual in an untenable situation.
Here's one relevant passage:
The handbook now includes being in a same-sex marriage under the definition of apostasy and as a circumstance that requires the convening of a disciplinary council. The handbook also clarifies that the ordinance of naming and blessing a child may not be performed for children living with a parent in a same-gender relationship.
I've seen, and I think we've all seen, children blessed and/or baptised who have parents who are living in various states of 'sin' according to Church teachings. Why single out children of same sex couples?
Here's another:
The handbook addition also states that "a natural or adopted child of a parent living in a same-gender relationship, whether the couple is married or cohabiting," can only be baptized, confirmed, ordained to the priesthood or serve a full-time mission with approval from the Office of the First Presidency. A mission or stake president may request approval and determine that: "the child accepts and is committed to live the teachings and doctrine of the church, and s
pecifically disavows the practice of same-gender cohabitation and marriage"; and "the child is of legal age and does not live with a parent who has lived or currently lives in a same-gender cohabitation relationship or marriage."
Note the bolded text. In other words, the child is required, in effect, to renounce his/her parents and declare their love/relationship to be invalid and requires the child to move outside of the household, which, in effect, is a show of disassociation from his/her parents.
You really think these are reasonable requirements?
Put yourself in the position of a child, who dearly loves his same sex parents, being required to disavow them and their relationship as a condition of full faith and membership in the Church. You still think this is reasonable.