This would seem to me to be a meaningful rebuttal if Ulbricht hadn't been charged with an inchoate crime. But he was charged with conspiracy, a parameterized charge, and so the overt acts listed in the indictment do in fact matter. See, for instance, model jury instructions for the crime of "Conspiracy" with "overt acts".

You're hung up on whether he's charged with murder, conspiracy, hacking, or whatever. I'm not. I don't care. The only thing I'm here to rebut is the pervasive meme that the Ulbricht murder-for-hire scheme was introduced informally by the prosecution in order to taint the jury and the judge. As you can plainly see, it wasn't: it was introduced in one of the most formal ways possible, in a manner that meant that its rebuttal at trial would have harmed the prosecution's case.