I thought it was normal for a prosecutor to present only one side to the grand jury. It looks like some ADA accidentally called a witness who revealed Cohen to be a damned liar though. That's not good for Bragg, even from the Dem point of view. Some prosecutors were not on board with Bragg's agenda. Some quit because of the witch hunt.
You are correct. The prosecutor only needs to present enough to get an indictment. But Bragg is getting too cute by half here. Now that it is known that he has withheld hundreds of documents that are favorable to Trump, that information will get to the GJ. It might not dissuade enough of them from indicting trump, but it could change a few minds. I honestly think fat ass knows he’s riding the dragon and he could fall at any moment.