The problem with that "decipherment", from what I've been told by others who are far more educated than I am, is that it does the equivalent of deciphering Anglo-Saxon runnic texts by using modern slang like "yo" in order for it to work out.
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.
