Found out a bit more now and he had a passenger despite being a learner rider with just 2 weeks riding experience. The road also had negative camber and i would think the young boy on the back might have leaned the wrong way. The lorry had crushed his torso so he has damaged spleen and liver plus ribs. He remains in a coma but i would expect them to keep him in that state. Probably brain damaged by lack of oxygen but its wait and see. He was physically very fit and 18 so he could fight back.
Just had to warn the Grandson who started scooter riding this week to half speed in rain and double distance from other vehicles.