Mallory-Weiss is indeed lacerations of the distal esophagus from forceful vomiting. Usually these are not fatal although i've taken care of cases where they are. In alcoholism with liver disease esophageal varices occur. This is a dilatation of the veins of the esophagus from portal hypertension secondary to the liver problem. This makes no mention if varices were present. Varices and Mallory-Weiss is a terrible combination.

The esophageal tears caused the bleeding (which in an alcoholic with varices would be massive) but the cause of death was the aspiration of blood. I've seen Mallory-Weiss tears without varices bleed massively requiring surgery to correct. Usually however the process is self limiting and no treatment is necessary. This would lead me to suspect something else going on with this patient.

The underlying liver problem (which sounds significant) probably contributed to the bleeding in a second way. The liver synthesizes many important proteins involved in the blood clotting process. When the liver doesn't work well the blood becomes "thin" and doesn't clot well....if at all. This, combined with bleeding varices is the death knell for a large number of end stage alcoholics.

Even mild varices (which may not have been seen at autopsy if not looked carefully for) and an altered coagulation status would set the stage for a massive bleed. Add to this an altered consciousness secondary to the cactus (although it is hard to imagine that the gag reflex would be decreased on mescaline).

I could imagine him initially having a large amount of bleeding which would/could decrease his sensorium (moving into stage III shock) followed by further vomiting and then aspiration. Usually people don't aspirate when they are fully conscious, and mescaline ought to make one more vigilant rather than comatose. This would make me presume that he initially bled enuf that he went unconscious, then had further vomiting. Vomiting in the unconscious state resulted in aspiration followed by death.