Penzance

I enjoyed listening to you on Episode 100 of the Cycling Europe podcast, so I looked at the Penzance guide as that's a place I know well - and when I saw cycle.travel/city/penzance/map?journey=3520 my heart stopped for a moment! 'Continue on A30' ! When the NCN uses the traffic-free promenade all the way from Penzance to Marazion (you can't actually cycle to St Michael's Mount, but that's by the by). How can it get this so wrong?