> ... do they really offer abandoned babies to just anyone...?

NO - the 2nd sentence of the article says that the adoptive-father-to-be had "a good job in social care". In the same jurisdiction as the baby was found.

So he's not some nice-guy rando who called 911 - he's a vetted and experienced professional within the same social care system as the judge, who that judge might easily have looked into before "asking if he had any interest".

EDIT: Yeah, in the course of the court hearing where he was testifying about having found the baby, the judge was probably sizing him up, and asking him questions well beyond his "briefly witnessed, called 911" role.