defense attorneys argued that Manhattan prosecutors had placed “highly prejudicial emphasis on official-acts evidence,” including Trump’s social media posts and witness testimony about Oval Office meetings

It’s unclear to me why an official act cannot be used as evidence that a different unofficial act occurred. Let’s say candidate Trump shoots Bob on Fifth Avenue and then, after being elected, threatens to “kill Joe the way [he] killed Bob” during his State of the Union address. He can’t be held accountable for threatening to kill Joe, but he did just confess that he killed Bob while he wasn’t president. Why couldn’t this confession be used as evidence in his trial for killing Bob? Or, for that matter, in his trial for killing Joe if he went on to kill Joe after he was out of office?