Robert warns Diablo about his risk. And he is pointing out that Diablo will just be used by Keith as a scapegoat.
Seeing Diablo is still hesitating, Robert says, "If you don't believe me, just go over there and listen to what he is saying right now. He is making another phone call."
Diablo laughs, "Ha ha ha ha ha, how do you know that I am not making him the scape goat?"
"Wait, no!" Robert reaches his hand out.
Diablo unzips his jacket and he shows that he is wearing several bombs strapped onto himself.
"What the hell!" Robert exclaims, "Diablo, what are you trying to do?"
"I am just one of the many people who are committed to do this. I am the true soldier, who is not afraid to march forward even if there is danger ahead. Unlike people who hide in the dark trying to ambush you."
Robert thinks he is referring to Keith. Despite Robert has no loyalty to Keith, he still doesn't want anyone to die because of Diablo's extreme action.