With a modern alloy crankset, alloy bars, levers, stem, rims, brake-calipers -plus plastic fenders and chainguard I bet a bike like this would weigh-in with a pretty respectable number compared to many modern IGH bikes you can buy.
This frame is pretty nice and very light for a lugged steel frame. The rest of the bike, other than the rear hub, could well be jettisoned to build a lightweight step-through commuter.