I saw a documentary on Gehry's work and I believe it stated that he is a designer, not an engineer. He designs with pen and paper, not a CAD system. I trust an architect to design a building to stand up under its own weight and not fall down because of the wind. The engineers are responsible for implementing the design. They are the ones who have the responsibility to keep the insides dry and choose materials that can take the stresses. Whether or not the engineers were working for the building contractors or Gehry's architecture business, I don't know.