User blog comment:Black Leg Sanji/BLS- Chapter 803 Review/@comment-24850639-20151007171604/@comment-67.204.208.3-20151008005506

Also, even though Kuma is now the WG's Robo-Butler, he started off as a Revolutionary infiltrator.

In other words, the Shichibukai system gave a Revolutionary personal access to the WG's greatest scientific asset: Vegapunk. Who knows what secrets he stole for Dragon while he was still in his right mind?