Seeing as this set up is explicitly prohibited by the UK CAA and wouldn't be allowed in the UK it does surprise me that just by being based in the Isle of Man they are allowed to get away with it, especially selling tickets on routes solely inside the United Kingdom.
Knowing people involved in the Cork accident and then reading further about it when the report came out, it shocks me even more that this sham 'airline' hasn't been shut down. I'm sure Van Air and their counterparts are all very reputable airlines but operating old, small aeroplanes on the opposite side of Europe to their maintenance bases with differing and sometimes conflicting instructions from their company and the ticket seller was a contributing factor in the Cork incident. I would hate for that to happen again.
Personally, I wouldn't be booking myself or any of my family through Citywing and I wish they would be a bit more open about the actual operation they are running.