What else Jinbei's gonna do lol?
Help out against CP0, of course. I mean, what else?
CP0 seems to be serious business. That means no amount of Lami and Lusopp can help. Robin and Chopper are down bad, so that leaves healthy Brook, injured Franky, injured Jinbei, and injured Cook.
Brook is not winning against the CP0 alone no matter how good he is. If you take Jinbei out of this fight, fortune then favors CP0 even more.
Zoro is going back to Kaido right after King, so he cannot help out against CP0. It literally has to be all the remaining SHs vs CP0