You're comparing apples to oranges. The Mathews & Fields traffic does not support the entire railroad. (Isn't there a second customer at the same location also?). In the discussion above, the issue was the track from Kodak to Folding Box. There appears to be no potential customers in that location other than the current operation. The whole area is mostly residential, including LONG term residential at Holy Sepulcher Cemetery. So increased traffic is very unlikely. The paper business is volatile and ownership of the plant has already changed hands recently. It might last 50 years but it might shut down tomorrow. Putting all your marbles in one small basket is not usually a good business proposition.
When you take all the various expenses (liability insurance, track maintenance, equipment maintenance, signals at 2 crossings, a place to keep the locomotive, accounting, various FRA mandated programs for training and certification, hirail truck vehicle insurance, employee wages and benefits, and MANY more items besides those - and we have not even talked about who buys the track from CSX and pays taxes on it) and figure the revenue those ballpark 150 cars will bring, it's not an attractive proposition.
I know, there are many examples of shoestring operations existing on very little. And we can play "what if..." all day to explain away various expenses. It's not totally impossible. It's just not likely.
You could wind up with a small fortune from that segment. All you have to do is start out with a big fortune.