Very interesting. Thanks for sharing. To say that Bruce wouldn't have died from cannabis because he had been taking it for a few hers is slightly wrong. Reactions can sometimes take years to reach a critical peak as ones immune defences are broken down through regular use. Also remember that when Bruce went to UCLA he was clean. He had stopped taking cannabis before his flight to the US. Remember that doctors mainly only find what a cause is when their actually looking for what they think is causing something. And that was the 70s so the doc probably just asked him to drop em and cough, then gave him a clean bill of health.
Also remember after the autopsy, the doctors noted that the equagesic pill was undigested in Bruce's stomach. The only other thing they found was partially digested cannabis.