User blog comment:Kaido King of the Beasts/Chapter 797: Daddy Issues/@comment-10543621-20150821001212/@comment-4889755-20150821014532

Oda needed a plot device for Luffy to be rushed and Rebecca to have another rason to be conflicted to go with him.

But I completely agree with you. I (along with others) really expected Luffy to take Gatz megaphone and say that Dressrosa was under his control now.