Hi Joe,
About the underlined part: you probably mean the "Hegdewar-Golwalkar" theory among others. But there was a great Notable of India's Freedom Movement who had postulated a similar theory; and I don't mean Sawarkar!
Do you mean Tilak? I'm a great fan of his, and am willing to forgive him his ridiculous book about The Arctic Home in the Vedas. Actually, the fascists had to distort it and tried to prove that the magnetic north pole was somewhere in Bihar/Gorakhpur, in order to get his theory to fit their own distortions. It's a hilarious story. But Tilak was a gifted amateur, like several other people who were learned in their lines and had no clue about history.
Be that as it might be; there is another theory about the origin of the Konkanastha Chitpavan Brahmins themselves. It runs thus: a ship-load of Jewish merchants were ship-wrecked off the Konkan coast. They came ashore, formed a settlement and became part of the community. Certain anthropological features persist; color of hair and eyes, facial features, body structure etc. Seems some-what plausible. Even Nissim Ezekiel (the late poet) had a take on this.