Some kune kune's dig, others don't. The following is our experience and feedback from other course participants over the years, the word 'tend' appears a lot below, and none of this is written in stone !!
It seems that if you buy piglets from breeders whose KK's don't dig, then as long as not restricted, they will tend not to dig.
If the piglet's mother is a digger, then the piglets tend to dig.
If restricted so that they have eaten the grass, they will start digging
Once they have learnt to dig, they will carry on digging even if then given a large area ! (a friend took on two from someone who had limited space, and they dug holes all over his 3 acres of grass!)
We have a pair of pet KK's bought from a breeder whose KK's have plenty of land and don't dig. They have 24 hour access to 3/4 acre of grass on heavy clay, and they have never dug a single hole - now 2 years old.
Now if someone says that the above is not true for them - I can only repeat the word 'tend' !