Hi,
they explained it actual in the video....
They said SOP requires engine shut down, when landing on the ship for refueling.
Because a pirate attack on a nearby merchant ship was ongoing, they choose the option of inflight refueling (pressure refueling) - which only lasted about two minutes to get enough gojuice to fly the 10 miles to the scene of action, covering the asses of the soldiers on the speedboots on their way.