Yeah, it's totally cohesive. Luffy smiles and laughs while fighting Kaidou who beat up a bunch of his friends, and threatens to enslave/kill his entire crew and the nation. He's rolling on the floor laughing while Vegapunk gets skewered and then runs away like a bitch while not caring where the rest of his crew is or even the fact that Vegapunk is dead. He lets himself and Zoro get beat up and spit on, and them and Nami get sorely humiliated, and does nothing.
But when defenseless and chained-up Loki says, "Shanks gay lol," he loses his cool and uses G4 to threaten him.
I really dislike the argument of Oda just wanting to copy/paste mythology. It's lazy, and also doesn't excuse damaging your own story's character for it. I don't think it's worth it.
If he wants to go that route, why not have Loki say something actually biting? Is Oda really so terrible at writing he could think of nothing better than, "Shanks is a pussy"? It's sad.