I see what he's saying, but there's something wrong with it. If you put a monetary value on a life, it means that you could increase utility by trading that life for more than that much money, because you could do things with that money that would increase other people's utility enough to make up for the life. But once you've traded the last life away, you can't use the money.

Robert A. Heinlein: An extinct species has no moral behaviour. ~An address to a Westpoint graduating class