In fact, as season 2 of Omega makes a caricature of him (not only of him, of everyone in fact), he said before as always:
"If possible, I would like not fighting."
Sure, Shun is a pacifist, and that’s the reason I love him.
But in Omega, he lost his empathy, and just says this sentence non stop to everyone, even obvious pure bastards (ep. 59).
In the original manga, he says that to Aphrodite (who doesn’t like violence), Io (who truly believes Poseidon works for the sake of mankind), and Sorrento (who survives and confronts the traitor). Not bad guys in fact. And he doesn’t say that immediately out of the blue, but after speaking a bit with them. He’s just naive in front of Charon. But here, his pure vision of “war is ugly, you kill good people” is seen.
In season 2 of Omega, he doesn’t seem to think of this points anymore, he’s just portrayed stuck with the “I don’t want to fight” that he says like a magic spell before every fight, without knowing a bit his opponent. I hate to say it, but he’s portrayed as a fool who just say that to clean his conscience. And that, it’s not Shun. It’s just the bad caricature I have read in some fanfics.
Note that this is for season 2. In season 1, he’s severely injured, yet chose to fight to protect young Bronzes against an obviously bad guy.
In season 3 we will learn all the characters were zombies control by Pluto.