Not sure what the issue is. Ford and others have been using aluminum body panels for years. The 2006 Expedition (and other years) had aluminum hoods and tailgates. They did not rot off the hinges or really had other issues. Some earlier ones had some corrosion issues due to poor factory prep prior to paint, but those issues seemed to have been solved.
Also aluminum structural components have been used without corrosion issues for years.
Agreed on the 150 time will tell, but the technology has been out there for over 10 years.