That was exactly my point one can not prove it therefore the statement should never have been made as fact.
No, as a rule it is difficult if not impossible to prove a negative. OTOH, we know for a fact that the pope has taken a vow of celibacy, we also know for a fact that he has risen to the top of an organization that values that vow. Given those facts, among others, and given the lack of evidence to the contrary, we can safely say that the assertion is true.