You Hindustani just don't seem to understand the geography of India.
Hindustan is a reasonable name for the modern republic of India. It is still distinct from Pakistan, even if you use that name.
Just because some Buddhists and Hindus once lived in coterminous Pakistan, that doesn't make it part of "Hindustan" or "India". This is part of the hindutva fraud. What has a pashtun tribe got to do with the river Ganga or the government of the republic of India sitting in Delhi. Neither the modern state of India/Hindustan, nor the ancient world gangetic tribes are connected to the majority of Pakistanis. We live off the river Indus. In fact, we are India. You lot are Hindustan or Gangadesh.
It's up to us right about what we should be called. We don't want to be called 'Gangu'. Should we decided for instance, what Pakistanis should be called? No, right?
Then please explain why it's an insult for any Indians to be associated with hinduism's sacred river. There is a contradiction here that warrants explanation by representatives of the Hindu rashtra - whether overt hindutva or "moderate" "secular" "Indians".
When I use the term "Gangadeshi" or its derivatives, there is no malice or negative inflection. Judge each situation on its context. Likewise, "jihadi" isn't necessarily an insult. Again, context is what matters. That was the example i referred to earlier hence I will use it again here.
Now if you wish me to desist from using Ganga and its derivatives in a purely descriptive manner, you need to explain why it is inaccurate as a geographical or geopolitical descriptor for India's people.
Again, I reiterate, I'm not talking about the term when used in a malicious context - certainly that should be banned and that is a case based assessment.