There's a huge difference between trying to get someone killed and calling for an election audit or objecting against the election results.
Are the Democrats guilty for all the BLM/Antifa murders? I don't think so and they supported and fuelled the protests/riots.
Were he charged with a crime, he would not.
Were he to file a civil lawsuit for defamation, he would have to prove the required elements of that case. In defamation law in the US, falsity is an element (in some other places truth is a defense, which is somewhat different), and for defamation against public figures, in the US, so is actual malice.
Note that both of those requirements have been found by the courts to be necessary to preserve Constitutional freedom of speech.
> There's a huge difference between trying to get someone killed and calling for an election audit or objecting against the election results.
Sure, and in court Cruz would have the opportunity show that he was only doing what you described and neither trying to get anyone killed nor doing anything that might reasonably be mistaken for that. But that's not something Cruz probably wants litigated in court of law, which is why he won't file and litigate a defamation claim.
Ted Cruz would have to prove, by a preponderance of the evidence, that he not only was not doing so, but that AOC actually knew, or reasonably should have known, he was not. Given that the specific notional basis for her accusations is her knowledge (and not only from public sources) of his involvement with the Jan. 6 insurrection, that’s probably not something he wants publicly litigated in a court of law, since it's something he desperately wants to erase from the minds of everyone not actually sympathetic to the insurrection, while still staying on the good side of the pro-insurrectionists.