Is it correct to play defensive high-lo or "echo" with two small honors?
Larry's advice is for when the card you play is winning the trick. When you're playing an honor that is lower than some other honor already played to the trick, play the top of touching honors.

This isn't an attitude signal (ie echo). This is communicating the honor layout of the suit.

Never* play an honor under a high honor unless you have the touching honor below it or it is a singleton. This signal allows partner to underlead to get to your hand if necessary.

*Never say never in bridge, but this is closer to true than "third hand high" and "eight ever, nine never."