I agree that a judge isn't God. Judges certainly make mistakes.
However, if the prosecution really had a problem with her order, they should have made a motion to change her ruling. If the judge wouldn't change her order, they could have moved for a mistrial on the grounds that they were not allowed to properly prepare. They could have taken it to the press -- don't you think talk radio would've loved that angle? They did none of those things. Instead, the prosecution chose to try for forgiveness rather than permission, and they got caught. Now they're paying for it.
I'm fuzzy on the facts, so I'm in no position to argue. I don't know how you can begin to hold a fair trial, though, by preventing witnesses from testifying.