The real problem with the Southern Tier between Binghamton and Campbell Hall is that Buffalo...formerly a major industrial center...is a fraction of its former self. The area originates/terminates much less traffic, along with most of upstate NY, so of course the rail lines would bypass it if other routes have better grades. And NYC, once a major industrial center, now imports most goods and exports 1. garbage and 2. financial products [also mostly garbage].
On the other hand, if there is enough truck traffic traveling the NYS Thruway, and CSX isn't capturing it, then a few grades and turns may not be such an obstacle for NS intermodal on the Southern Tier. Replacing a >>135<< year old bridge would help increase train speeds to be more truck-competitive.
135 years old? Its not even steel! Just wrought iron. The Portage Bridge must be just waiting to fall down.