It's possible (and I'm not making this claim, just pointing out the possibility) that the type of person who's life can be saved as cheaply as possible is contributing less net good to the lives of other people than the average person (who is self sufficient). In real-world terms, it is plausible that the latter is more likely to support a family or even donate money. I'm not saying that some people have more intrinsic value - but the deaths of some people might weigh more heavily on the survivors than the deaths of others.

Please see the sentence after the one you quoted.

That is why I felt the need to point out that other people who are reading this conversation should not use the (correct) observation you made about extreme altruists and apply it to themselves

I felt (and feel) obliged to point out to the same people that it is often an error to be persuaded to do Y by someone telling you that "X is no excuse not to do Y". Accepting that kind of framing can amount to allowing another to modify your preferences. Allowing others to change your preferences tends to be disadvantageous.