I disagree Groundhog, NQY could become profitable if they turned it in to a camping & caravan site, holiday accommodation, theme park etc.
Obviously the chopper needs a mainland operating base but, even without a new heliport, I agree that operations to/from NQY would kill it, there are a number of airfields in Cornwall and several of them closer to the Scillies, and a railway, than the other side of St. Mawgan airfield.