> weeks of overseas travel where nobody knows him and he doesn't talk much are great fun for him

This sounds like me. I once went to a week long conference where I realized at the end that during the entire week I could count on 2 hands the number of words I had spoken to other people during that time. I don't have the desire or need to speak with other people. I'm happy with my own thoughts. Or as Jane Austen wrote, "Her own thoughts and reflections were habitually her best companions."