The only reason one can think of is that TVC-Tata, ERS-Hatia are already there to cater to the large migrant workforce going towrds Jharkhand,Bihar from Kerala. But probably there might be a need for a dedicated train to cater to the huge migrant workforce for the TUP, CBE , Salem belt. Maybe that could be one reason. Tirunelveli-Danapur is there for South TN. So maybe one more. Couple of years ago they did run Coimbatore-Asansol spl as well.