"The limits are unknowable while setting upper and lower limits necessarily limits what can be known."
Unobservable, untestable claims do not advance knowledge. That will always be the case.
Ever seen a penguin fly? Or know of anybody that has?
Awareness of what we are unlikely to learn from research using the scientific method advances knowledge. Awareness of what we don't know advances knowledge. In short awareness of ignorance both in the present, as well as the smaller subset of what will likely remain beyond our understanding, in the sense of being resolved or even addressed with useful effect by the scientific method, advances knowledge. JMO.