Because von Braun was the thinker in charge, there is a certain scale to this kind of credit. The US government gets credit for the Manhattan project, but not as much as Oppenheimer who gets more than the guys who assembled the bomb.
He provided nothing new? Besides a first hand account of the war, ignoring the treasure trove of information that he knew about other events and such during the previous cycle.
And the people who developed and built the bomb deserve the most credit since it wouldn't exist without them, just like Javik's plan then and Javik now wouldn't exist if it wasn't for the Protheans who developed and built the facility and cryopods.
The part Javik was directly in charge and involved in failed.
We already had firsthand accounts of the war, and his accounts provide no value for this war. While the lore of his cycle was interesting, it too had no practical value to this cycle.
I feel neither of us are going to budge on this.