It may have been done to minimize the crossovers at Dankuni. Moreover, specials don't get enough respect to have a proper running slot, how can we expect one to get a shorter route where the prestigious trains run.
At least Bandel could've been made a halt, it isn't doing any track burning run in HBM anyways. But being an NR train, it's being run in NR sense, i.e. without any real sense. Perhaps, they thought they could run it on whatever route is free, like they sometimes did on the BSB-LKO lines.