Interestingly it's not far out on a limb for him as he's 2m (6'7") tall and has had to see an orthopaedic recently about ongoing knee issues, so...
I can see a case for a doctor justifying WTP or Club Europe as the seat pitch in the Traveller cabins would be pretty uncomfortable for a 6ft 7ins gent with knee problems, but I think justifying Club World is a bit difficult.
We warned that Ayling character that introducing WTP would mean corporate customers downgrading their First ttravellers to Club and Club travellers to WTP but he wouldn't listen!