I did not know there was a limitation.
Imagine this scenario:
A couple dies (for whatever reason) and the children go under guardianship of one of the couple’s siblings, who is a single gay man. I do not see anything wrong with this scenario. The kids go under the protection of their uncle. And technically, their uncle is committing no sin by being a single gay man.
Same thing applies if the guardian sibling of the couple is a divorced woman, or a single man. Being “different” I do not think disqualifies a person automatically. And if they eventually sin/go against the teachings of the church because of their sexual preference, how are couples, who are likewise everyday sinners of something else, be any better than them, just because the couple is in a recognised marriage?
Does not make sense to me, but I don’t know the rules.
PS. I know of a (die hard) catholic single lady who adopted a baby daughter. The little girl is now 12, and her mom is still single. And man o man….I would love to see other catholic couples teach their children what this single lady teaches her daughter. I would not be surprised if the little girl became a nun. Excellent example of a single mom, adopting, and teaching her child, pure and straight forward catholic values.
2ndPS: Just to note, that she eventually found out that her baby girl was born muslim, and the first thing she had done when the adoption came through was to have her baptised, not really knowing the history of the little girl. One more soul for our team!