He said it was Marijuana. However, did he say he died from too much marijuana smoke inhalation, or THC? Also, did he give out the THC and other cannabinoid levels found in his body? To come to a conclusion, the report has to be as unbiased as possible. Clearly if there were no THC levels reported, or any other cannabinoid levels reported, then it most likely was not the cause of death. If it was, why would the doctor hesitate to post such detailed information? Also, it is estimated that toxic THC levels have to be around 30,000 - 40,000 times that of the average dose to get stoned. And by estimated, I mean that since nobody has been documented to die from THC, that nobody actually knows the exact ratio. This means a very, very extreme THC level. So extreme that it is humanly impossible to smoke enough grade-A bud within such a short time period.
Don't get me wrong, I don't think cannabis is harmless. However, a direct death caused by toxic THC levels is indeed unheard of. Birdgirl is correct in what she says, though. There are many angles to view this from.

Sombrero, lethal doses also depend on body mass and tolerance. However, I would not doubt that 10,000mg of caffeine could kill everyone who tried that dose. So of course a "lethal dose" would be 10 grams. However, even 8,000mg would likely kill anyone. That's just an overestimated dosage, so that it is definitely correct, because it all depends on body mass and tolerance.

Cheers