mate, grand jury hearings can be completely secret and the accused need not be present. Word is they’ve already indicted him under the Espionage Act 1917 in a hearing in Virginia
What you say about grand juries is true, but so what? The grand jury hearing occurs in the pre-trial stage. It doesn’t replace a trial. I don’t see the difference between a prosecutor deciding to indict someone and having twelve people conclude that an indictment should be issued, except that in the latter case there’s a chance the twelve people might decide not to issue the indictment.
EDIT: Grand juries are a right someone accused of a crime in the United States has. They’re an extra step that make trials (slightly) more burdensome for a prosecutor. They’re not a means of circumventing justice.