This is something you'd learn in your first year at law school. If, as Trump's complaint alleges, Dominion did destroy evidence then the evidence is immediately assumed to support the opposing party's allegations.
Biden's defense would now have to prove there was no fraud as if Trump's team had certain evidence of there being such.
When canvassing boards certify results and state legislatures approve electors, they are affirming that the election and tabulation were conducted fairly and according to applicable laws.
Given the obvious levels of fraud committed, anyone advancing the false claim that the election was fairly conducted, whether through signature, vote, or public statements, is part of the conspiracy and deserves to be punished.
Never cede the null hypothesis when it is rightfully yours.