People expect him to be able to go to war and have the mentality to deal with the enemy just like that? lol please. It's quite normal to have doubts and fear, especially when you've been living in protected luxury your whole life. Doesn't matter how old you are and it's consistent with the fact that he's a normal adult citizen of Japan, a modern day peaceful country.
But in terms of his personality in dealing with others like at the war meeting, it's true there does feel to be inconsistencies that suggest childish regression.