Failed Adoptions at Age 18

So reports the New York Times:
Lamar West has lost parents twice in his life. The first time was when he was 4; the second was a month before his 18th birthday. The circumstances differed, but the outcomes did not.
       
When Mr. West, 20, tries to remember his biological parents, his eyes close and his face goes still. He remembers his mother’s name, Rochelle Griffin. Then he recalls a place — a hallway, an office — and fragments of conversation. “Records. Drug abuse. Termination.”

At age 5, Mr. West was adopted from the Illinois child welfare system. His four siblings went elsewhere. Parental rights were terminated. His child welfare case was closed. His last name and birth certificate were changed, listing his adopter, Frankie Lee West, as his mother. He had a new family.
       
He lived in Ms. West’s Roseland home with her and her eight other children (six of them were adopted) for years. But in 2008, he went to stay nearby with a family friend for a few months because Ms. West’s new house on the Southwest Side had become too crowded. He remained in regular contact with her. Then, in January 2009, he went to her home and discovered it empty.

She had moved — “upped and went,” as Mr. West said — to Atlanta. It was a month before he turned 18, and a month before the checks she received from the child welfare system on behalf of Mr. West were scheduled to stop.
       
“I’ve never felt pain like that before,” Mr. West said of finding the empty house. “My heart was beating so fast. It was like someone was punching me from the inside of my chest.”

Mr. West is what caseworkers and providers refer to as a “failed adoption.” He is part of a growing group that is entering the local shelter system for homeless youths after their families vanish as quickly as the government checks attached to them do.       
This is a failed adoption, isn't it?  The idea isn't just to get the kid to 18, and then all bets are off, right?  Sure, there's no legal obligation for a parent to support a child past 18, but what does it say when the relationship ends as soon as the adoption subsidy checks do?