Just in case you did not know, Indus script remains undeciohered as of now. It has been reasonably established that there is continuity of peoples and culture in the Haryana region since the pre-Harappan times to the modern times. That should not be a surprise.So you think Iravatham Mahadevan is a Dravidian nationalist? (Tamil Brahmin)
So you think Asko Parpola is a Dravidian nationalist? (Finnish Sanskrit and Tamil scholar)
So you think Painted Grey Ware is evidence for Harappan culture, although they used Black and red ware?
So you think Black and red ware in South India is not material evidence?
So you think bricks and drainage system in Keezhadi is not material evidence?
So you think Indus script in Keezhadi is not material evidence?
And since when is a Rosetta stone required to decipher a script? A Rosetta stone helps, but in our case it was not required.
Maybe an eminent "Vedic scientist" converted all Harappans to use Painted Grey Ware while a "Vedic doctor" transformed the Indian expatriates in Europe to have fair and lovely skin by plastic surgery..
What Mahadevan and Parpola were/are means nothing to deciphering the Indus script. They are/were not successful in doing that.