The effects of the drugs caused his dumb ass to go to sleep.
The fact that he happened to be in a pool of water, of his own accord, while taking the drug, is on him and him alone.
This was recreational negligence, not an accident.
In situations like this, people look to prosecute the provider rather than take full account that the user was using and sought to use. Like when Mac Miller unfortunately overdosed and they looked to demonize the person that sold him the drugs and prostitutes he sought for. Now had the person who sold either of these two overdoses NOT sold them, they (The users) would have continued seeking from someone else, but to act like as if they were mislead or forced to take the drugs they were looking for..is just a weird look in my opinion.