Because he had to drop could turkey in order to line up with his worldview (can’t preach that modern medicine is poison if you’re having to taper off benzos). In reality, it’s likely that the combination was the coma and the drug withdrawals - benzo withdrawal can quite literally kill you because your brain needs them to function at that point. This is why he went to a Russian clinic, because literally no doctor anywhere in the West was willing to take the risk of “oh this guy might straight up die and we’ll be left holding the bag”.