The right political response should be to strengthen workers bargaining position---run the economy hot enough to turn the labour market into a sellers market, and keep enough social safety net that even just saying No without another job lined up would be feasible.
"Since this move accomplishes exactly the curcumvention of the strike, we consider the new company bound by the old company's agreements. Oblige by Monday or stop flying in Norway".
(Police and school teachers have similar requirements in their contracts and will use "sick-outs" to apply pressure without a full strike)
Second - a company that would cross the unions by hiring new workers would be blockaded. First by the union itself, but very soon by other unions. For example a restaurant that doesn't pay the correct wages might not be able to get deliveries of certain products, garbage won't be picked up etc. Outside the entrance customers are handed flyers that the restaurant is mistreating staff. All of this is regardless of whether the restaurant staff wants to be union members and regardless of whether they are happy with their contracts.
And this is working very well actually - there is for example no need for minimum wages set by law. Strikes are rare, and "illegal/wild" strikes outside of contract periods are almost unheard of. Perhaps surprisingly, businesses are quite happy with this setup. Weaker unions would likely mean more unnecessary strikes, and definitely more regulation of things that are now covered by agreements.
But as alkonaut was pointing out, the actual rules themselves don't matter as much to business as predictable and swift enforcement.