Anything that can not be verified
Is not a 'fact', it is simple assertion. As such it has no role in any empirical or scientific discussion, analysis or exploration. Deductively speaking, the best that can be said from anything derived from such an assertion is that the derived conclusions are no more true or false than the original assertion.
Deductively, inductively and scientifically- throwing around statements like 'I read once upon a time in a 100 year old text that I can't remember, locate nor produce a fact that, if incorrect, destroys my asserted hypothesis' makes everyone in the room with any training seriously wonder if they should even bother speaking to you.