Trump's no lawyer. He was crudely expressing one of the legal arguments being made by his legal team - that the election results disclose a number of statistical anamolies that, when considered together, shift the burden of proof to the responding parties to explain, and in the absence of a persuasive explanation, justify the request for an audit of the election and/or other relief. Trump knows better than to try to talk with the precision of a lawyer, and also knows better than to try to communicate to the general public that way.
However, taken in context, Trump's statement did not suggest that he gets to remain President without winning a legal case or without decertification of the vote by the applicable State legislatures.