How much Coke was he snorting to die from snorting? My impression is that most drug overdoses arise from shooting up drugs. You would sooner puke before overdosing off Coke...again, depending on the quantity snorted. Did he snort like 10 grams in 10 minutes? That's what George Jung said he did, if the move Blow is accurate.
It's not so much the amount of drugs...
1 line can kill you if the 'perfect storm' is happening within...
BP off the scale, liver screaming, irregular heart beat, dehydrated, etc.
Any of these factors mixed with the internal biological effects of illegal drugs could have contributed.
I had a friend who was a HUGE abuser of coke...the man was a vaccum! He woke one morning and had his usual 'C and C' as he called it - coffee and coke. He was found on his kitchen floor later that day. His first line of the day killed him.