2 things
1) The group and zoro has Sommers’ heart, which directly affect Imu’s condition. Imu has already implied that the death of a Holy Knight impacts him, so destroying heart (which zoro the one who suggest that lol ) is going to weaken him. That creates a clear motive Imu would need to retrieve it, and if Zoro is the one protecting it then it leads to imu vs zoro
2)Chopper’s Devil Fruit is important to Imu. Since his abilities counters Imu’s powers in some way, Imu would naturally target him. The fact that Oda places Chopper right next to Zoro in this moment could be intentional, setting up a scenario where Zoro steps in as Chopper’s protector.
So
With both Sommers’ heart and Chopper being key targets, Zoro could be the one forced to fight against Imu