I mean, all deaths are accompanied by cardiac arrest - it just means your heart has stopped, which every heart does in death. The issue is WHY/HOW it stopped - what caused the cardiac arrest? Bronchitis on its own doesn’t cause cardiac arrest (myocarditis can, but that’s beyond bronchitis). I’m not saying it was a conspiracy and the guy was killed, but I am saying “he died of cardiac arrest” is about as telling as “he died when his body hit the ground” - WHY did his body hit the ground? Did he fall? Jump? Was he pushed? Was he previously at a great height or did he trip while walking at ground level and only died because his head his a curb? Or did he fall because he was shot or hit by a car and the bit about the ground is a red herring?

I also assume his brother, like most family, is upset over the sudden, unexpected loss of a loved one. And like most family, there’s a good chance one member is a bit of a lunatic, conspiracy theorist, or just prone to lashing out when upset rather than calmly accepting horrific news with the stoicism of a Buddhist monk. So even though I think it’s bs to claim he died of cardiac arrest with zero follow up on what caused the cardiac arrest, I also think that most people would be upset enough to sound crazy after their sibling died, especially if they don’t have answers (because cardiac arrest is not an answer).