Facts of life: the feed the dairy people use is shipped from the Midwest to someplace in the Valley (Sacto? Stockton? lots of options over there) then trucked to Marin and Petaluma. Once upon a time the feed mills in the North Bay did get shipments by rail - though as with all things it'd hard to make a living with a RR based on one shipper or even one commodity because life isn't like that. Things change all the time and you need a whole bunch of accounts to make it work.

The advantage of a "short line" is that they can pay attention to smaller accounts. They can aggregate shipments from and to a bunch of small (a few cars a week) shippers and present the mainline with a big enough package to make it worth their while. In theory at least, for a price (which hopefully doesn't make the trucks look cheaper), and understanding that UP (NWP's only potential mainline connection) prefers to ship trains not loose cars. And as we've heard in some other threads not all short lines are created (or have evolved to be) equal when it comes to customer service - if NWP hopes to even survive commercially (let alone make a profit) they will have to be better than average and their ability to do that is untested in the current rail environment.