I'm not very familiar with the details of that example. I know the whole idea of predatory pricing has not generally held up to scrutiny.

Crushing your competition is much more difficult in practice than it's usually given credit for. Even if you put all the other steel producers out of business, you can't just arbitrarily raise prices, because there are substitutes for steel that weren't crushed. As prices rise, people adjust their production techniques to use more of the substitutes and eventually new steel producers reenter the market.

In every case I'm aware of, the losses incurred during the undercutting stage were larger than any gains from the reduced competition.