User blog comment:SuicidalSkydiver/Kuma a revolutionary?/@comment-423448-20100603000943

That was actually my first thought the second I saw him. I think that it is, without a doubt, Kuma. My reason being because if you recall an earlier chapter (I can't remember which on), Ivankov mentions they used to be allies when Doflamingo tells him the Kuma he knew is "dead".