Its probably because the line is intended to be a dedicated freight yard line (There is some leveling visible beside the EMD that looks like a freight loading area). Such platforms are called single face platforms. When one side of an island platform holds a freight loading line, then that side is usually fenced off to discourage people from getting into the wagons or trying to cross the tracks from under the freight wagon.
Similarly at stations where less traffic is expected, or stations on mainlines which are mainly passing stations, they fence off platforms to allow the use of the track for freight or for through trains to skip the station without a PSR.