Julian Assange should just admit to these claims. These accusations are backed by evidence of the transfer of messages between Wikileaks' staff and Trump's camp. Though he's claiming foul play, the collaboration between Julian Assange and Russia had some history behind it and we see they had an intention of influencing the election in Trump's favour.
Wikileaks suspicion of releasing emails hacked from the Democratic National Committee, Wikileaks' publishing of one or more of Trump's father’s tax returns in order to make his group’s attacks on Hillary Clinton seem less biased, Wikileaks' tweet of an attack on Clinton for not having driven her own car during her decades of public service.. all are evidenced with proof that pins Julian Assange.
Well the damage on Hillary Clinton is already done and Julian Assange at the moment has nothing to lose since he's objective was successful.