There seems to be some frivolous use of the word "blame" vs. the word "responsibility".
Both pilots had the responsibility to safely conduct their flight, including a basic see and avoid obligation.
While the investigation isn't over and findings released, it doesn't seem like either pilot willfully or otherwise violated any rules. That pretty much eliminates word games over "blame". HOWEVER, it is likely that both pilots failed to see and avoid other traffic, which was BOTH of their obligation.
That tells me that there is a shared "responsibility" for the mishap. And guess what - the dead guy might not be dead if he had taken his obligation more seriously and gone beyond the minimum required by the rules. As a fast mover driver with extensive safety and mishap training myself, I can say that sometimes even in spite of the best traffic callouts, you just don't see the other aircraft.
So, we have 2 pilots. One is dead and, if given a second chance, might take the trouble to contact ATC for flight following. The other is alive and he probably deeply wishes he was "better" and could have gotten the SA on the Cessna in time to avoid the collision. Blame? Hah. Both pilots probably could have been "better", especially in accomplishing tasks upon which their lives depend. There's your responsibility and obligation, fully shared by both pilots. Blame? I wouldn't dare assign blame in this case especially since I haven't seen either the factual information or an investigation report. But from an outside perspective from someone who has been there and seen nearly identical mishaps take place, on the face of it there appears to be a failure in a shared responsibility among all involved.
Armchair lawyers and people who don't know jack about real aviation can point their ignorant fingers and try to assign blame, and you can bet your butt that there are lawyers right now trying to come up with the right words to convince an uneducated court jury and audience that there is in fact "blame" to assign to a single party in the mishap.
Regarding the US method of conducting separate safety and accident investigations for military aviation mishaps... Those lawyers are the reason why safety investigation results aren't given to lawyers, because they twist things so badly askew that no pilot with any sense at all would ever cooperate with a safety investigator if they knew the lawyers would get a chance to mis-represent their testimony in court. In Europe, the pilot is assumed guilty and the lawyers just need to find any trivial mistake or act, even as dumb as skipping a healthy breakfast before flight, to pin the entire liability for the mishap on the pilot. I'm glad I don't fly in Europe because that liability-focused investigative process is a bigger threat to me than anything else I've faced in 25 years of military flying. The Iraqis might have loved to shoot me down when I was flying over their country, but they weren't trying to ruin my family too.