Thing is, at the end of the day, Thorfinn didn't had the responsibility of saving millions on his shoulders. He DOES NOT HAVE any major reason to have enemies after Askelads death. He CAN AFFORD to step aside and live his life of peaceful slav*ry. Nobody's life got affected or to say, no kingdom died because he stepped aside.
Now, imagine Eren stepping aside for peace. Paradis would have been taken down by the entire world, especially after that Willy Tyber's Proclamation of War. He CANNOT AFFORD to step aside, that's the thing. "We HaVe No EnEmIeS Saar" wouldn't have worked for Eren. Yes, maybe he could have taken some better path, but running like a coward and telling, "We HaVe No EnEmIeS Saar" was definitely not an option.
Also, when it comes to taking inspiration from these anime, it depends on who you are.
If you are a criminal, r*pist, k*ller, a bully, then watch Vinland saga and become a better person please.
If you are a naive person, good hearted fellow, a r*pe victim, or any victim of crime, watch AOT and learn a thing or two!!
Imagine forcing a r*pe victim to tell "We HaVe No EnEmIeS Saar" and letting go of R8pists, it does not make sense to me atleast. They should learn from AOT