Grilling Redfish on the Halfshell : Butter or Olive Oil/EVOO?

Grilling some reds tonight for the family before the Super Bowl.

I typically make a melted butter mixture to coat the fish before a light dry rub dusting prior to cooking. I was told yesterday that using Olive Oil instead of Butter caused the fish to be more "flaky." I have always found them to be flaky with butter, that the meat of the fish determined the "flakiness."

Is there truth to this or is my friend a "flake?"