If Bush and Cheney would of went on the record about 911 then you'd have a leg to stand on. By them refusing to go on the record is definitely an indication of guilt or deception of some sort. If you believe he refused to go on the record because he was innocent, then you're the one in need of zoloft!
Just for fun, let's look at the stupidity of this statement.
First of all, there is something called the presumption of innocence in the United States. That is, you have to have proof to accuse someone of a crime. You simply cannot accuse them, then attempt to condemn them for refusing to testify.
If you have a case, make it. If not, quit embarrassing yourself. Not talking about something, or not wanting to talk about something, proves absolutely nothing.
Then we have this pearl...
I can't recall any case where an innocent person refused to go on the record or testify.
Actually, it happens quite a lot. One example, to quote the recent papers, involves the Ramseys, who never talked to the police and have finally been exonerated.
That's why Grand Juries detain people who refuse to tesitfy, because it gives them reason to the believe they're hiding something, innocent people are motivated to clear their names.
A witness who refuses to testify without legal justification will be held in contempt of court, and is subject to incarceration for the remaining term of the grand jury. A witness who testifies falsely may be separately prosecuted for perjury.
You're obviously not a lawyer, and neither am I, but apparently I understand how the law works slightly better than you.
Grand Juries do nothing other than indict people. They can't detain anyone. Judges do that. A Grand Jury doesn't indict anyone without a lengthy investigation by the police and a positive recommendation for charges from a prosecutor. At that point, they have nothing to do with what happens.
To return to your Bush/Cheney whine, I need to look at my 9/11 report, which is packed at the moment, but I tend to recall that both interviewed with the committee, as did Clinton.