"Locking the door for a short time is not by itself abusive, but for some groups (for example, foster parents) and in some places (for example, some provinces of Canada) it is illegal. If you have a really difficult child, you should check what regulations apply to your situation and get some professional advice."

(This is after recommending Dutch doors or barricading your child in their room, and before explaining ways to handle the destruction caused by a trapped child)

Some stuff is usable but I can't take all of this seriously. It may have worked for the author but I think we know better nowadays.