He did preface his comment by saying Americans have an expectation of 10 rounds as opposed to 20 or 30 when referencing handguns. What I found interesting is that he asserts the magazine is an asset of the handgun and is to be included in the phrase "in common use". That he discusses the concept of magazine capacity without assigning a number, discussing the configuration of the handgun for example, is an excellent approach. He rejects, properly I think, that there is a magic and defensible number of rounds allowed.
I thought his time and place comments were interesting.