I was on holiday in Turkey last year and dozens of these things were to be seen bombing up and down pavements and walkways. I saw two accidents (one quite serious where both the rider and the pedestrian she collided with seemed quite badly hurt).
I don’t know why District Judge Rosenberg is prevaricating. I believe (as others have pointed out here) that the law is quite straightforward and that these vehicles should seek type approval (which they are unlikely to get), and their riders should be covered by Third Party insurance, and they should not be driven on the pavement. If DJ Rosenberg believes the law is complex he should hnad the case over to a bench of Magistrates.
Mr Coates, of course, is bound to believe the thing is safe. That’s because he has not collided with anybody yet.