They might be doing some sort of glass chop in areas (actually, i wouldnt be surprised if this is what they mean by “composit body panels”, open molds would be cheap as hell, and parts are cheap too), but I used to use that more for body panels or exterior details than anything super structural. I guess they could do fiberglass frame rails, but that still feels like it would be a strange choice at what just doing basic ladder frame in steel would cost.