Yes, he really could be happy and excited about it.
My whole life growing up we moved every 2-3 years. Yes, there were times when it upset me, especially as I grew older but the rewards were much greater - which I couldn't even see at the time. One of the last moves before I became an adult was when I was about 12. I can remember that one clearly and at that point I actually looked forward to it. I'm sure he has mixed feelings - it is the same about any "positive" major change in your life but he sees things on a much smaller scale.
Moving has added so much to my life. Now 40, I am lucky enough to have continued traveling my whole life and even took a job in my early twenties that was 100% travel. I am now settled down with a family and have a real sense of fufillment. Thanks to my parents taking the chance and moving the family (a huge undertaking) - I have an appreciation for much of the rest of the world and feel like I've done it!
And nothing is as good as actually living in the country. You get so many more experience and see what it is "really" like.
Let him have all of the feelings associated with it - it is just not a black and white thing. Just know that it will be a gift that he has with him for the rest of his life.