Good analysis; thanks for bringing it up.
The stupidity of it all is that Biden didn't have to say anything. He was there in his capacity as Vice President to support Hillary for President, not talk about Japan's connection to its postwar Constitution. He should have been talking about how wonderful her achievements are...except we all know she hasn't achieved anything, so he had to think of something else to talk about.
Moreover, you, me, and everyone else here knows that he's madder than hell on the inside that is isn't BIDEN who is the candidate and Hillary giving the "I support him" speech, and that will occasionally spill over into what he says.
Good Point