We're not trying a case here, so I'm not sure to what extent proximate cause applies.
Whether or not Trump should have been trying to kill Soleimani might also be relevant. Suppose a kid doing something causes a chain of events that leads to an accident. Are things different with regard to the accident if what the kid was doing was something he wasn't supposed to be doing? It seems so! In that case, a lot of people would be like, "LOOK WHAT YOU DID!"