I didn't thoroughly read the whole thing...but it sounded like he was saying John Calvin believed modern day Jews will be saved due to the pre-Christ covenant with Abraham--without faith in Christ.
I have never heard Calvin taught anything like this....which is in essence 2 ways of salvation.
Clearly covenant theology builds a greater link with the Old Testament than any other Christian theology, however, like the New Testament, and other orthodox theologies, proclaims after Messiah came, for all people, Jew and gentile alike, faith in Christ alone saves.
Well not according to Calvin and predestination...