Give us a break.
Clearly the U.S. "steel industry" was NOT hurt by any such things.
Quite the contrary. Often the metallurgical firms have broad production interests, and steel and aluminum are conjointly held. Kaiser Aluminum and Steel was one such example.
This was a mere rhetorical argument...with no substance.
Exchange the word "theoretical" for "rhetorical" with regard to the steel industry and I'll agree. On the other hand, the substitution effect is an economic maxim. I'm not sure that's what you mean, however.