I believe he was actually referring to Omega, who the Allegans used to subjugate Bahamut in the past.

He follows this statement by saying he will return to Ala Mhigo to see the "prize" for himself. You will see in the climax of Stormblood that the Garleans got a hold of

Shinryu. This seems to be the moment when he receives the report about the Garleans finding Shinryu and its state after its fight with Omega.