"Objectionable content", "Hurting religious sentiments" are the reasons given when github/ vimeo/ pastebin etc., were banned few years ago. The rationale is pretty vague and it's often tough to understand on what info a certain site gets blocked.
I would assume it's much the same as Canada's law against publishing hate speech. Just with a very wide net on what constitutes hate speech.
I think someone mentioned that politicians in India enjoy wide freedoms due to generous libel laws as well.