Why.... seriously why

Why on god blue earth did Berlioz just shoot some random MT....WITH A OGOTO? ISN'T THAT LIKE ONE OF THE STRONGEST WEAPON IN THE GAME?! I get that he don't underestimate his opponent but seriously MT?

Why on god blue earth did Berlioz just shoot some random MT....WITH A OGOTO? ISN'T THAT LIKE ONE OF THE STRONGEST WEAPON IN THE GAME?! I get that he don't underestimate his opponent but seriously MT?