So I didnt know what to compare for the orders of magnitude.
Like you said, by death it's more than 4 (since as far as i know no one has died yet).
But by affected area, toxicity normalized mass of spill, amount of ground water affected, etc, I don't know how they compare. And a cursory search showed it would be hard to get clean data.
But any way you slice it, you're right. Two orders of mag is not enough. Bohpal was such a tragedy :(