I have read only a few books/articles of modern authors on Hinduism. Hence, I do not know whether I am qualified to write an answer on this subject. Still, I am offering my opinion.
I am reproducing the guideline mentioned in the question content.
In the absence of any scriptural reference, written works of scholars,
researchers and popular personalities can be used which must be
providing a relevant answer.
As far as I understood, the phrase in the above sentence - In the absence of any scriptural reference, is an elusive statement.
It is because
- The member, who posts an answer to a question, might not have read all available scriptures properly. Still, he/she may claim that no such reference is available in the scriptures. Who is going to judge the claim of the member?
For example, let us consider an imaginary question - Whether Krishna, son of Devaki, mentioned in Mahabharata and Puranas, was mentioned in the Veda, brAhmanAs, Upanishads?
Let us assume that the questioner is not interested in whether same Krishna that was mentioned in Mahabharata and Puranas had been mentioned in the above scriptures.
Not many members might not have read Upanishads, brAhmanAs, leave alone the Veda. Majority of the members may not be knowing the answer.
At this juncture, a member may quote a modern day scholar's article, in which the author might have made some denigrating remarks on the very existence of Krishna, the son of Devaki.
So, in the above scenario, though there was a mention in the Chandogya Upanishad about Krishna, the son of Devaki, in the scenario of ignorance of a particular Upanishad, may leave majority members speachless and have to accept the denigrating remarks of the modern day scholar.
Is it acceptable? I will leave it to the judgement of the majority of the members.
- Now let us take another scenario.
A modern day scholar, who is very keen in knowing about Sanatana Dharma aka Hinduism, might have visited many times, discussed the many aspects of Hinduism with the then available Gurus/scholars of India. That scholar at a later date may write many books in highlighting the noble SPIRITUAL concepts, as enunciated in the Veda, Brahmanas, etc.
I am referring to authors like David Frawley.
Are we allowed to accept the reference to those books, in our answers?
Let members decide. I stop here.