Yes. He keeps asking for proof about his own accusations that have no proof. 
There's actually a term for it... Argument from ignorance.
http://en.wikipedia.org/wiki/Argument_from_ignorance
"also known as appeal to ignorance (in which ignorance stands for "lack of evidence to the contrary"), is a fallacy in informal logic. It asserts that a proposition is true because it has not yet been proven false (or vice versa). This represents a type of false dichotomy"