Re: Sumo: light vs heavy and IS?
It depends on what you call "Aiki".
I would say he used Aiki because he made his attackers intention and action (ki) fit together (ai) with his own intention and actions.
He clearly demonstrations the four necessary steps to make an Aiki interaction. Kokyu (he is calm, grounded, and present) Musubi (he makes a connection with his partners mind, binding it with his own) Awase, (that very nice blend he used) and Musubi, (he stayed connected after the blend was over). That is what I would call Aiki.