I have to agree with you. She didn't leave and shut him in there by himself either as a pp had stated, I don't think there is even a door on the laundry room. She was in there washing vomit out of the nice comforter they had just bought and the other children were going in and out of there, then Jon did take him to the floor in their room, nothing wrong with that, since he had just vomited in his bed and it was probably wet and nasty.
Suzanne
she left him in the laundry room and turned off the light. If there was no door, I stand corrected. It's been a while since I've seen that episode.
It just really struck me as cold.

this is another DIS thread about that episode - the OP mentions a closed door, too:
http://www.disboards.com/showthread.php?t=1751119&referrerid=93883