I did notice that one, but aluminum is kind of a complex topic (https://en.wikipedia.org/wiki/Aluminium#Synthesis_of_metal): the early cost was both the chemical processing and the low ore content, and one could charitably read him as referring to discovering bauxite and the electrolysis method, and then he's certainly right about the cost of electricity coming down drastically and making aluminum even cheaper. So not clearly wrong IMO, given that it's an extemporaneous interview.