I wouldn't think it was strange that he lived with his mom if he had not recently had a baby and was planning on getting married. The home Kelsey lived in would have been adequate for the three of them, I would think.
I've been thinking the same thing, but then I read one of the links this morning where her family said they didn't live together because he had financial issues related to the price of beef.
I wonder if her parents supported her purchase of her home with the condition that he cannot move in with her, that he has to provide a home for her or at least share 50/50 investment. It's not unusual for parents to take the position that they'll provide for a daughter but not for a man who does not even marry their pregnant daughter.