The former villains received forgiveness for their past misdeeds, before the existence of Krakoa. Shaw committed crimes while in Krakoa, and thus must be face judgment for his present actions.
They were not random russians. They were members of Verendi, a group that were literally giving money to people who murdered mutants.
The law states: "Murder no man"
Not...
"Maim and Hurt no Man"
Lord Ewing *Praise His name! Uplift Him in song!* Your divine works will be remembered and glorified in worship for all eternity. Amen!
The issue after Kate dies, Bishop only manages to discover her body by infiltrating a Verendi ship, who wanted to get her corpse to harvest her DNA. The ship Shaw used to surprise Kate and kill her was also owned by a Verendi member, Donald Pierce.
If you mean the mission in which the Marauders went to destroy the power dampeners, that also happened bc Bishop infiltrated the Verendi systems, discovering a russian faction which was selling the power dampeners to the government. Again, Verendi members
Kitty should have told Kurt what happened. I think Kurt would have messed Shaw up real bad.