The term "aluminium component" does not mean that the entire enclosure is made of aluminium, but rather that a "component" of it is made of aluminium, e.g. the frame to which the plastic enclosure is fixed, clamping parts, etc. It is not specified how high the aluminium content is or exactly which components are to be made of aluminium.
But yes, the marketing of "aluminium components" was a bit exaggerated here...