"Daddy Went to Safety School"

At the local playground today, my nieces met, and were playing with, a
6-year-old neighborhood girl who was at the park with her nanny. For
some reason, the child took a real ****ne to me, offering numerous
random details about her life, both at home and at school.

At one point, the girl looked at me and said: "My daddy doesn't live
with Mommy and me anymore. He had to go to Safety School. He might
come back someday, or he might never come home to live with us again.
I have to wait and see."

I felt a cold chill on the back of my neck. Until then, I'd just
smiled and nodded, pretending to be interested by everything she told
me. But this statement piqued my curiosity. "What is Safety School
exactly?" I asked.

"When I was 4, Daddy left me in the car all alone in a parking lot,"
she explained. "Some police found me and took me to the Police
Station. It was really scary. My Mom had to come and pick me up. So
Daddy has to go to Safety School."

I am trying to decode this statement. Obviously the mother had
explained the situation to the child in terms she could understand.
But what is "Safety School" is a euphemism for?