Is Marshal Xi Rui the only one who can undertake this mission?
Not necessarily.
The Alliance also has excellent generals available. Whether it's the two battle groups or commanders like Yan Fangxu and Perbov, they can assume this role.
Just as Gu Hang has had various plans for dealing with the remnants of the Northern Line Army, even if Xi Rui and Qin Zhiping are incompetent, it wouldn't hinder Gu Hang's grand strategy.
However, if he didn't consider the remnants of the North Line at all, Gu Hang would have to leave behind not only generals but also a portion of the troops to serve as a feint.
The troops that are left behind can't be weak; otherwise, the feint won't work, and it could even show weakness, allowing the Insect Race to push them back in a counterattack, leading to a loss outweighing the gain.
