You can tell it's being done for adult convenience, not safety, because the children are forced into oubliettes and then ignored. When parents lock a child in a closet, it's recognized as abuse; when teachers or doctors do it, that's condoned.
If it were really about safety, the child would be put in a separate room with a teacher to continue the lesson or a school counselor to go over coping skills or at least model civil behavior, through a picture window or a viewscreen. Safety may require separation but in no way requires isolation. So when it does include isolation, you know that adults simply want nothing to do with the child -- or think they can get their way by means of torture. Require adults to provide interaction during separation and watch them drop the technique like a hot rock.