Matt Simmons was a LONG TERM threat to big oil because he was most knowledgeable and able to find alternative means of energy production.
I believe that a heart attack usually causes the person to STOP BREATHING. If that was what happened, he wouldn't be able to BREATHE IN water so as to drown? Either he would have still had enough energy and consciousness to get out of the water or...NOT "breathe into' his lungs the water.
DROWNING is when you "BREATHE IN" water, not when water simply SEEPS IN to the lungs (suffocation).
Doesn't it seem strange that a coroners' report cites TWO causes for a persons' death?