Sure, but currently India is represented as a purely Islamic culture. The only civ within the entire Indian subcontinental region is the Delhi Sultanate. And they're adding a variant civ which is just one specific dynasty within the Delhi Sultanate. So it has no Hindu representation whatsoever. Which is an even worse representation than claiming it's 100% Hindu as a matter of history, and in the current Hindu supremacist culture in India, the problem is just amplified.

If they wanted to make a variant civ to represent Hindu India, they could do it. It might face that cultural backlash, but "variant civs" have already been used for political bodies that aren't directly related to their parent civ. All "variant civ" means is that they share a lot of game mechanics. Abbasids and Ayyubids are both Islamic, but don't have a lot in common beyond that. Holy Roman Empire and the Order of the Dragon (which is most associated with south eastern Europe) are likewise only tenuously connected. Making a Chola Dynasty civ as a variant of the Delhi Sultanate would not feel great IMO, but it could be done, and would be better than not having any Hindu representation in the game.