This move by Railways needs to be revisited on the following grounds:
1 Nature's Call can't be predictable and it's an emergency
2 It will create serious problems for all specially elder people, kids and mothers and sisters
3 It will create serious problems for people having ailments in heart, kidneys etc
4...
more... It will also create immense problems for people having dysentery and IBS(Irritable Bowel Syndrome)
Rather this system needs to be modified on the grounds of cleanliness in the stations by duly considering the problems of Train Passengers.
If Bio-Toilets can be made possible to install in all Coaches of IR like Airplane then I think no such restriction will be required.
(It's not a Correct Solution, the Correct Solution is equip all Coaches with Bio-Toilet ASAP)