How would you explain the reluctance of the soldier to leave the shelter of the doctor’s home even when he knew he couldn’t stay there without risk to the doctor and himself?

When the American war prisoner came to consciousness and realized that he was saved by a Japanese family, he feared that he will be soon handed over to the army. However, as he noticed the amount of concern and care given to him by the family, he understood that he was in safe hands. He knew that although he was a threat to the doctor’s family, his own life might be saved there. Burdened with gratitude towards the family, he ultimately decides to comply with what the doctor planned for him - the escape.