Why do I have the feeling one of the main outcomes of this is PostNord loses business of deliverying the license plates and other courier gets the tender instead?
You can’t have a “should not respect strikes” clause in your tender, especially not as a government agency
It would require however that there are other couriers that fulfill their safety requirements with the logistic infrastructure to deliver to the entire country. That's not likely. But entirely within the realm of possibility that someone with deep pockets could start one.
However it would not make any difference for Tesla, as that courier would also be unionized. Few other companies would do business with them otherwise, as Tesla is about to find out.