An Independent regulator is required for PPP projects so that there is level playing field. Even if the haulage charge is unreasonably high, the private operator has no option but to pay, as they have no other option. On the other hand IR does not wanting to subsidise the luxury travel is justified.
But what should be the reasonable haulage charges should be decided by an independent regulator keeping in view the haulage charges being collected by other railway systems round the world.