We show departures from nearby stations based on either straight line distance or rail distance whichever is greater. As you correctly observed, Bhavnagar is 50km from Dahej by sea, but many times more by land/rail.
So, for all practical purposes, it should not be classified as a "nearby station". We shall have look into the search algorithm and modify it for anomalous situations like this.
Anyhow, it will be corrected soon. Thanks a lot for the observation.