If you are at low health, using commander's grab on terminus is a really bad idea. Because Terminus is a large character, he doesnt go over Khan's head after the throw so he gets a free hit and gets closer to Khan which is what you do not want.
Khan's Ultimate will throw Terminus away. If he has Shatterfall he can stop the momentum. He needs cc reduction 70% to do this. Instead be near a ledge before you grab him then aim diagonally down offstage to guarantee Terminus dies.