He was literally made to be, narratively, the catalyst for Mankind's comeback. That's his entire fucking purpose and the reason he works so damn well. Had he won shit wouldn't have been half as good, as his defeat is meant to make you feel both invested and bitter with the Gods, he's essentially Eren's or Edward's mom, so the next point has more merit—
Nippon stronk! Jap wank! Ofc japanese people win!
—Literally any-fucking-body in the third place would've won because of Adam and humanity's 2 consecutive defeats. It being Sasaki was the best option because that would make the absolutely fucking narratively obvious win sweeter and more interesting, as Sasaki is a character only/mostly known for getting his ass kicked by the
actual strongest swordmaster back there in Japan, so he's the ultimate underdog.
Why do you guys have to make everything about ethnicity. Don't you ever get tired of being miserable and petty.