"As a person from an upper caste background may I ask you why you think the criteria for reservation should be economic when the bias is because of caste?"

Quote from the article you have provided: "With money. Somebody who does not have access to money does not have access to “merit”."

And I agree with Yashica Dutt's analysis. It is true that irrespective of caste, if you have enough financial power, you can change your circumstances, particularly in India. Hence, it makes sense to have an affirmative action that benefits those who are economically underprivileged, than on basis of birth.