No expert as well but hot rolling rail is little different than hot rolling an I-beam or any other structural member, but you need the tooling (presses, mills, etc.). Algoma used to roll rail but as far as know now only produces coil and plate. I have no clue how long it would take and how much it would cost the re-tool.
Stelco is owned by US-based Cleveland-Cliffs and Dofasco is owned by EU-based ArcelorMittal.
There's going to be a major push to have Canadian steel in our 'nation building projects', including military modernization. Given the amount of steel they would be looking for and the number of Canadian-owned mills, I'm not sure we have the capacity to meet it all.