I studied your link and find (so far) as follows: The more recent hypothesis A) that the Indo-European civilisation began in Kurgistan 7000 years ago instead of in India, irrespecive of whether that civilisation spoke Sanskrit or not at whatever period in history offers neither support nor counter-argument to the hypothesis B) that Sanskrit is the origin of English and so A irrelevant to B.

To put it another way Sanskrit is indeed the classical language of India, the objections you raise (or should I say link to) are only relevant to whether or not it originated in India but are not relevant to whether or not Sanskrit is the origin of English.