I think the single word lines are appropriate for him. According to his lore: he was part of a race of people that functioned as a "superorganism or hive." Therefore he would have most likely have a very basic thought process meant to be part of an accumulative consciousness. As such, having single word lines reflects this basic thought process. He is on a mission to "kill" his enemies by "hurting" them and inflicting "pain." The last line of his lore also states, "Malphite has also begun to change, as he has been forced to face his own profound loneliness among the world's vibrant individuality." The lines you mention above and the performance of them, gives a sort of double entendre when you consider that he might be hurting and in pain because of his loneliness.