It wasn't actually that exact amount. It was "about 12 tons", and somebody did the 12000 kg / 29g calculation and used the answer with way too many significant digits. Probably the reporter trying to make the 12 ton number relatable.

(You might object that KitKats usually weigh 40g. So these were probably the new KitKat Icon F1 chocolates, which weigh exactly 29g.)