Why would a factory in the US want to position itself to use rail nowadays when all major railroads’ prime focus is intermodal traffic?

The class ones generally don’t want it unless it is delivered to them in a trailer or container, and if you’ve got it in a truck already, why not send it that way the whole journey? It will usually be delivered faster, more reliability, and often cheaper due to the subsidized highway system.

If you have a single carload or more, you’ll be lucky if your friendly neighborhood UP or NS decides it’s in their interest to deliver and spot your cars, then they MIGHT return to pick it up when it suits them, which is whenever the PSR algorithm dictates.