An ACE member I know that met us there when we went recently pointed out that Steelers Country sort of ends abruptly right where Steel Curtain’s exit is, despite there being a bit of land back behind it. He thinks it could be for a flat ride, such as a drop tower called Terrible Tower.
According to the Kennywood rumor mill, Steel Curtain was a test investment to see if a big coaster could bring people in, and if it did they could actually start making more investments like it. Again, heard this at an ACE event so not at all a reliable source but it sounds plausible.