That is not a rail spur. It's the main line.

The rail spur dropping off to the right continues on to the Occidental Chemical property. That is clear here:

https://maps.google.com/maps?q=43.079447,-79....h&z=18

So unless that track became unused since the Google pic was taken in 2011, that is not the unused rail spur.

Did Occidental stop running cars to their property?

If anything it's the broken down spur to the north, which seems to also not be on JBII property.