Well, he didn't seem to be very cooperative with the Gorosei during the Dressrossa arc. Maybe it's hinting at him switching sides
My stance on the Final war hasn't changed, in fact, with the Holy Knights I'm even more confident in my scenario.
The alliance let by the PK crew will defeat the Navy while at the same time Dragon and the Revs get the scabbards treatment at the holy land, then Luffy and the others advance to finish the job.