The only thing that might be a drawback on that stamp is that
(and don't laugh here) many foreigners (westerners)
look the same to Japanese so they might understand the Uncle Sam image but they might not look close enough to see it is G. Bush. Again, remember, all foreigners look alike to many Japanese.
I have seen some 'look alike' contests in Japan where foreigners (Americans/westerners) were supposed to look like famous people, and they would have been booed off the stage in the States, but for the Japanese they were 'close enough'.