I tend to disagree with the statement the British were actually in a good shape to save Norway from German occupation on the longer term, since the British had no forces left to force their will on land, due to the BEF in France. Naval action was more logical, combined with soem minor movements of landforces, that were anyway illequipped to fight at all.
On the Altmark Case itself, the Brtiish could affort to continue action against the Gemran ships, due to the intelligence they had on British Civillians onbaord the German vessel. Even with Norwegean resisistance offered, the Norwegeans could not actually prefent the Brtiish from doing things their own way. At the worst, it could deterriorate relations a bit, untill the Germans invaded with force, still drawing the Norwegean into Allied hands. The OTL would still be the follow-up of the action anyway. (including the invassion of Norway by much better equipped German forces, who had dominance in the skies and with the OTL naval losses to both sides, including HMS Glorious.)