SOunds to me like the sting did not kill him, but was more of a traumatic injury.. From the reports I have seen, he was stabbed in the heart but the stinger or what ever it is called.. If that is the case a few diffrent things could have happend causing his death.
First would be the stinger being large cut his cornary artery ( artery that suplies blood to the heart) and he sufferd a heart attack secondary to trauma.
Or,, The stinger punctured the heart filling the scak that surrounds the heart with blood untill the pressure was so great that it could no longer beat,
Or the venum got into the muscle layer of the heart causing it to become paralized..
Either way is it sad to see him go. But he gave his life for something he truley loved. People say poor him, but I say poor us. For he went through life with a passion and a love for live, while the rest of us sit at home and wish we did this, or want to do that.