The Biden administration said it will appeal a federal court ruling that it resume a "Remain in Mexico" program for some migrants.
As well they should
ALL THINGS HUMAN
HOMO SUM; HUMANI NIL A ME ALIENUM PUTO.
Why not undo “Remain in Mexico” the way it was done?
Presumably because of the delay involved and the safety of the migrants. See, e.g., https://www.humanrightsfirst.org/resource/mexico-still-not-safe-refugees-and-migrants (from 2018 but I doubt much has changed since).