Maybe from a gameplay point of view, but lorewise Angra is perfect. I don't know the specifics myself, but basically, Angra Mainyu is conceptualy an Anti-Human superweapon the likes only Type Mercury and Primate Murder can match. It doesn't matter if his opponent is infinetly more powerful than even the strongest Servant, if it's human, Angra can kill it. And this Lostbelt's king matches that description to a T.
