Dont think it is of any benefit to Kerala. Rather the state should be spending energies on completion of doubling between ERS-TVC (via Kottayam & Allp), exploring starting train services (local, demu) ,from Cochin harbour terminus, old Ernakulam station, developing pit lines in Palakkad Town & Ernakulam
Land is already available, all that it requires is some long term thinking and the urgency to implement. Coach factory does not necessarily mean that kerala trains will get good coaches . Having a coach factory in Perambur or Kapurthala did not mean that TN & Punjab had the best trains with good coaches.