That's not how it works. The burden of proof is on him:

When two parties are in a discussion and one makes a claim that the other disputes, the one who makes the claim typically has a burden of proof to justify or substantiate that claim especially when it challenges a perceived status quo.[1] This is also stated in Hitchens's razor, which declares that "what may be asserted without evidence, may be dismissed without evidence." Carl Sagan proposed a related criterion – "extraordinary claims require extraordinary evidence" – which is known as the Sagan standard.

That's from wikipedia https://en.wikipedia.org/wiki/Burden_of_proof_(philosophy)