Norton has as far as I know never specified a max weight.
The bike itself weighs about 170 kg meaning that the driver should not be above 65 kg! if the 235kg would be true. Maybe that would be possible just after the war but nowadays an average driver with a weigth of 70 to 80 kg is more usual, meaning that this bike could almost not be ridden in Norway.
This cannot be true.
The MC's were used with pillion equipment meaning two adults are able to be transported. 2 adults of 35 to 40 kg each seem rather unlikely to me.
I can only say that the max weight given in your paperwork is not correct.
I do not know on what information the civil servants have based the max weight. It is more likely to be between 285 to 300 kg or even higher.
Maybe it is known for an BSA M20. That is the same class of bike.