Purely based on the content of the website, I fail to see anywhere on the website allusions to Hindu Nationalism. The website contains a paper from acadamia.edu showing their analysis. Lastly the claim about "Brahmin circles" also seems malicious because it is being discussed on mainstream media like CNN-News18 or IIT Hyderabad.
https://www.academia.edu/78867798/A_cryptanalytic_decipherme...
As a non-linguist, non-Sankrit speaker I can't evaluate those claims, but considering that this script declines as the Indus Valley Civilization fades away, along with the arrival of Indo-European speakers who would be more likely to speak the ancestor language of Sanskrit, I'd be highly skeptical of these claims.
If the script is a full writing system, and I were forced to guess what a future decipherment might find, it wouldn't surprise me to see that the language is related to the Dravidian languages.
Hopefully more examples of the writing will be found so that we may one day know for sure.
If we can decipher letters from burnt, rolled up scrolls, I’m sure eventually we’ll figure out what IVCs writings meant.
Sanskrit is a language that goes beyond Hinduism. Almost all important Buddhist Sutras and influential works like Mulamadhyamakkarika or Jaina works like Tattvartha Sutra are in Sanskrit.
Lastly Sanskrit is also the language of many secular works like Siddhanta Shiromani, Sushruta Samhita, Kama Sutra or Abhigyanashakuntalam.
btw why is it wrong for Hindus to say about their history. Should we allow only White Christian historians? Critic the text not the person. Please stop with outdated racist views.