He did not choke on his own vomit and so do many websites in your search
"After years of illicit drug taking it's ironic that the prescription drug Heminevrin, prescribed to wean Keith off alcohol, would be the drug that killed him. A post mortem confirmed there were 32 tablets in his system at the time, 26 of which were undissolved. The conspiracy theorists tell us that he was too experienced a drug user to have accidentally overdosed, that his death was in fact a suicide. Some, including John Entwistle, believe Moon choked to death, that his muscles were just too relaxed to vomit"