The suicide story will probably never go away, because it's too good a story. It fits so neatly into popular culture.
How would he have put himself quietly to bed if he had gotten a fatal dose of cyanide in the spare room where the electroplating was taking place? Wouldn't there be very fast respiratory distress?
It is not outside the realm of possibility that he became confused and in pain, decided to lie down to sleep it off, then died in his sleep. My own father in law suffered a significant blow to the head and, despite knowing all the signs of a concussion and what to do about them, got up and slept it off- the very last thing one should do. He was simply too confused to do anything else.
His story had a happier ending than Alan's, but it goes to show that the accidental death theory isn't implausible.
It may or may not lead to a coma, but I surely wouldn't let someone sleep one off immediately following the injury if I can help it.