It is not necessary. The trolls gave this frozen off-paneled fight 10 times more attention than Oda did.
Keeping Zoro and Lucci frozen this long is intentional, he is baiting them into betting against Zoro like he did in Wano.
Your analysis is correct, they havent done much and they had the same scuff marks since before they started.
Zoro is casually keeping him busy and they are afraid of how potentially easy Zoro can deal with the guy Luffy needed 3 moves in G5.
I personally think the fight is not Zoro's but Jinbe's, I said he would fight Lucci even before he went after Zoro.
The only remaining threats on the island are Kizaru, Lucci and Saturn.
Jinbe gets Lucci, Zoro gets Kizaru while Luffy and Sanji gang up on Saturn, paralleling Skypiea's team-up.
Now they fear what Zoro might do to Lucci but soon they will fear Jinbo.