Evidence of traumatic brain injury in Maine shooter who killed 18

Honestly, I am not buying the attempted explanation of grenades possibly causing the TBI. Let's think about it, every single SM that had exposure to grenades, both LIVE and TRAINING grenades, we all should then, by this explanation, have TBI. By this explanation, I should have TBI from all the IDF that landed 100 yards from me. I do not believe this dude was standing anywhere near the explosions of live grenades.