I want to enable comments for a reader one hour after they read a piece.

The idea is that you'd have to remember what you had to say, and will have had an hour to let the ideas in the piece sink in.

You'd still have the same moderation tools you could delete spam, off-topic or abusive comments. But this would eliminate the drive-by slammers. And people who have a standard speech they want to give and don't care about your time.