I am not seeing this as Zoro being afraid, he is stepping up to them all, besides Kizaru, because he was already at the verge of death, but he did not show fear from him.
Notice, Sanji who is visibly shaken, indicated by the movement around him in the panel.
Brook's and Robin's reaction, compared to Zoro's in the Kizaru ones. Nami as well.
Usopp's reaction to Kuma compared to Zoro's.