> Is that an actual EA argument?

you missed this part: "The arguments always feel to me too similar"

> The value is all at the margins. Like Carnegie had legitimate functional businesses that would be profitable without Pinkerton's. So without Pinkerton's he'd still be able to afford probably every philanthropic thing he did so it doesn't justify it.

That isn't what OP was engaging with though, they aren't asking for you to answer the question 'what could Carnegie have done better' they are saying 'the philosophy seems to be arguing this particular thing'.