I agree that it's a hell of an experience and must have been a great adventure for a 17 year old, and he deserves every congratulation for having achieved it.
That said, as a Cirrus pilot myself: it's not a technically difficult trip to fly, and several other Cirrus pilots have actually already done it, albeit not at the age of 17. FWIW, there is one Cirrus pilot currently posting on COPA who has done this trip and, having upgraded to a PC12 is now doing a polar circumnavigation. Sorting the logistics and funding are probably much more difficult than the actual flying!
Despite this, there's no doubt that it was potentially dangerous as it involved a number of long over-water flights in a SEP but, as the recent chute pull on the ferry flight to Australia showed: good planning, which I'm sure Lachlan would have had, can go a long way towards mitigating the risk.