Got to dusk off that old Money and Banking text book. Fed buys and sells treasuries all the time, it's part of their open market operations....
Not that it means anything, but i agree with your take on this. Another factor that might have played a role in the case of Japan is that Japan is a nation of savers, whereas the US is a nation of spenders and borrowers. Deflation is not nearly so bad for savers as it is for borrowers.