^^ Welcome to the Forum.

That is unacceptable in my book. I'd be very interested in what the dealer/Ford has to say. Corrosion on aluminum panels is covered for 5 years, unlimited mileage but rust is another thing. Surface rust caused by exposure to the elements is not covered, The Corrosion Coverage Period covers sheet metal panels and is also for 5 years, unlimited mileage but only applies if the panel becomes perforated due to a manufacturing defect.
The picture seems to show surface rust that isn't perforated. Good luck.
Peter