When Kuma reveals himself at Thriller Bark, he qualifies the reveal: he is a government human weapon that is not finished.
The payoff
(The army-scale Marineford deployment is a further escalation that lands forward of this window; the finished-model / mass-production reveal itself is on-page @0511. See Pacifistas Built To Look Identical To Bartholomew Kuma for the Kuma-template thread, which stays pending.)
Why this matters
“Not yet complete” is one of Oda’s tightest chekhov-explicit tells: a stated incompleteness that the narrative is obliged to complete. Pairing it with Vegapunk’s named genius pre-loads a World-Government weapons program rather than a one-off enforcer. See Pacifista.