User blog comment:Xilinoc/Ch. 587 - The Headless Star 6 (for real this time)/@comment-2211792-20140703125145/@comment-11051098-20140704171145

Many fights are happening at the same time. Maybe Ichigo arrived just as Bazz-B and Shinji were about to fight, and Bazz-B decided to ditch Shinji and go for the real thing. Besides, Kubo already had Shinji easily defeated by Bambietta, I doubt he would do that again, off screen, with the same character.

The others who showed up to surround Ichigo might have wanted to fight him too, or they just wanted to make sure he couldn't reach Yhwach.