User blog comment:Kaido King of the Beasts/Chapter 797: Daddy Issues/@comment-5869646-20150820073935/@comment-12.106.174.131-20150820142755

Another thought on Law/Sengoku, Law might have tried picking up where Cora-san left off in taking down Doflamingo. It is possible that Sengoku has been working with him ever since and could have had a hand in getting him the status as warlord for the access Law wanted.