Because there are no details of the case. A kid made up a story because she was mad at her parents. The state took the kids and now they won't give them back because they don't want to look like the fools they are for believing a childs unsubstantiated accusations. Now they are just holding on to the kids trying to fabricate some excuse to take them permanantly.
I know it sounds evil but this is standard operating procedure for government employees. Never admit to a mistake. Ruin families, reputations, lives, but never admit to a mistake.