Why did they let the owners have the dog back?
I don’t think the pound could rescind ownership, unless the owners were mistreating it.
Don't know the exact reason but here's my theory:
City of San Bernardino is broke (declaring bankruptcy)and their shelter is always overcrowded, which will become worse after July 4. The shelter personnel thought Oso would be better with the original family than certain death if not rescued. The SB shelter is often hard too work with so this might be the best solution for now.
If this were City of Irvine's shelter they would have not gotten the dog back. I was ready to call the Irvine shelter if they could get Oso as they will get other dogs from high kill shelters when there is room.