1. It was their Task to make people quit, and thats exactly what they did.
2. Digangana had a CHOICE of saying NO. She didn't. The HM's try to portray themselves as team players and then you have to make some sacrificies for it. If not, just say no, its simple. Whats the worst that could happen? Losing the task? Prince getting nominated?
If something were hurting my religious sentiments, all the above consequences would be really small for me. Contestants have got to learn to PRIORITISE before cribbing.
Digangana had the option of saying NO, whereas Rishab wasnt even aware of what Kishwar did to his water, else he wouldn't have drunk it. Which is why Salman said 'uske saamne hi thook ke de dete'.
3. Personally, I don't think it was as big an issue for Digangana as she made it out to be, else she would have quit just as she did later about going swimming.