Well earlier in the war France and Britain were considering sending an expeditionary force to Finland to help them fight the Soviets. Sweden did not allow them to use their territory to pass, because they feared that the Allies would occupy the iron mining center in the north of Finland (which would have basically brought Sweden into the war against Germany) and the Winter war finished soon after anyway.
At the end of the day they might have made the right choice. Who knows what would have happened if the allies went to war with the USSR, their alliance to Germany might have lasted much longer.
The Winter war finished because Stalin whole strategy was not to go to war with Germany or the Allies before the were at war with each other.
He knew very well that France/Britain were seriously considering action, not just in Finland. A far larger danger would have been a massive attack by the RAF on Baku targeting the oil fields.
The reason the Winter war ended with such comparatively good terms is that Stalin had to end it or risk escalation.
At the end of the day they might have made the right choice. Who knows what would have happened if the allies went to war with the USSR, their alliance to Germany might have lasted much longer.