But your response is definitely the best argument against it I've seen.
They knew the license terms when they bid for the spectrum. One of the approved uses is providing internet service, and the license agreement (UASL) specifically says that this entails providing access to all legal websites and services on the internet.
While the intent is clear, it isn't as detailed as net neutrality legislation in other countries — which is why campaigners want new regulations or legislation with similar clarity as laws in Brazil, Chile or the FCC's rules.
Now the question is why should some business be treated as utility, it is because they control access to limited natural resource, which somewhat prevents free competition
The tariff and regulatory structure of telephony is different from internet access. "Telephony Neutrality" basically says that you can call anybody you like as long as you can afford it and you are free to receive phone calls from anybody.
Internet.org is thus more like: "you can call these toll free numbers, but you cannot receive calls from anybody we haven't preapproved".
There is nothing magical about the IP address of internet.org that makes packets to and from it special. Hence zerorating should be applied to either all IP addresses or none.
This is not going to happen the way the Indian telecoms are screwing up Net Neutrality. Internet.org is only part of the problem. Indian telecoms want to charge extra for OTT (over the top) services. This includes many internet messaging (ex: whatsapp) and VOIP (ex: skype) services. Internet.org sets a bad precedent where the telecoms can come up with various packages that are "free" while charging exorbitant amounts of money for the rest of the internet.