They'd better not be - but they should be stainless or plated so they won't corrode.

And +1 on this being pointless - the ISO 6-bolt hubs work great, so exactly what problem is being solved here? If they want to machine custom hubs, put an ISO 6-bolt pattern on both sides so that I can choose between running 2 ratios in a flip-flop setup, or a cog on one side and brake on the other.

Or a dual-disc setup on the front... Or on the rear of a chainless downhill bike!