In rail operations there are many factors at play including crew deployment, crew linkage & utilisation, availability of staff for maintenance, loco change, shunting & so on, whether the station has adequate facilities for ensuring staff has resting place and other things. Unfortunately its a fact that all these constraints are observed in smaller pass through stations. In this case I have heard that Palani was being explored, but since it is a pass through stn MDU division was unwilling to spare staff just for the maintenance of this one train if it was terminated there. For now terminating at PGTN seems more from an operational point of view.