The Revolutionary Army doesn't have enough man power to take down the World Government and the Marines, so why the heck would Dragon give up Kuma, one of his strongest fighters, to the WG. He obviously has some kind of plan in place.
I think Vegapunk may secretly be against the WG. Naturally their greatest scientist would be in the safety of Mariejois and would be a witness to all the corruption and atrocities of the Nobles. He may also be heavily opressed and overworked by them and actually hates them but they aren't allowing him to leave. Perhaps Vegapunk, through Kuma, may have made contact with Dragon and is now another undercover member of the RevoArmy. Thus when Vegapunk upgraded Kuma he implemented some sort of fail-safe so that when the time came he could easily switch Kuma back to his original senses albeit with his new upgrades, in the mean time he has been supplying info to Dragon. Vegapunk could also have a similar to turn all the "new" Pacifistas against the WG, greatly increasing the RA power.
Just a thought.
#SAITAMA STOMPZ _your.name.here_