AFAIK as soon as the aircraft has departed the paved surface it becomes a notifiable incident to the AAIB and the a/c should not be moved until the AAIB give the OK ?
Do you have a source for that statement?
I'm not suggesting we strap on our spurs (or tundra tyres) for every situation, or that I'd have tried off-roading in this instance, but just for some perspective here's the Fluff operating far from any paved surface:
https://i.stack.imgur.com/Hx4my.jpg