It is really simple.
First, the market data proves definitively that the tweet in question was not material since it precipitated no market movement. That is a quite definitive standard, one which the SEC must apply if they pursue a civil or criminal action.
Second, if the SEC chose to pursue legal action claiming a violation, they must prove their assertion.
Third, if proof of immateriality is present, but teh SEC chose to proceed anyway, they must prove their own case.
Their own case allegedly relied on TSLA share traders providing evidence, which must be presented to prove their case.
Of course, if they wish to avoid discovery they can drop their case and void the original agreement that precipitated their assertions.
It's a civil action, the plaintiff has no alternative other than present their evidence unless they wish to drop the case. Their standard of proof is less in a civil than a criminal case, and the SEC has rarely pursued such cases, almost never in the absence of clear criminal action in violation of an agreement.