the accident was another sign of the dangers of oil drilling
The premise behind that statement is that an increase in U.S. oil production (without a concurrent increase in the number of oil pipelines) goes hand-in-hand with more freight traffic, and an increase in train traffic will result in more accidents.
That and Bakken fuel is high volatility and a more dangerous freight than regular crude oil.
I suspect the CSX oil train derailment resulted from the deluge of rain Virginia and Maryland received at the time (> 4-5 inches in a day). It caused a street embankment collapse in Baltimore that closed a CSX track. The day after the oil spill in Virginia, there was a CSX coal freight train derailment in Bowie, Maryland, which had "no environmental impact." Two bad days for CSX.