Why don’t we have some system in place that can step in and say, “This trial is not being appropriately handled. Let’s make some changes so that we can be sure the legal system works as intended.”
I’ve never seen such a Show Trial.
We do. It's called the appeals process and it's meant to make sure that if a judge errs then his decision can be overturned. The problem is that if Sullivan goes ahead with sentencing Flynn then in addition to opening a judicial sh*t-storm it ends the process for Flynn. People who plead guilty generally give up their rights to appeal. It's not impossible to appeal, but it makes it harder.