Are all statements true until proven otherwise? He spoke, with no substantiation, at a conservative conference denouncing a contributor to the democratic party

Are all statements true until proven otherwise? He spoke, with no substantiation, at a conservative conference denouncing a contributor to the democratic party. Not only is that venue suspicious but any real counter intelligence conversation is done discretely. So perhaps the burden of proof is actually on him. And perhaps the requirements for such are rather high. And if anything, his actions strongly discount rather than support his claim.