Couldn’t agree with you more, but this is a New York court, a New York Judge and a Trump-hating New York jury.
Then this is where the "speedy trial" part of the Constitution comes into play.
If Merchan is continuing the trial knowing that the prosecution has failed to make its case, then that is simply the government using the trial to drain the resources of the defendant and illegally keeping him gagged and in the courtroom. This is what the "speedy trial" protection was meant to prevent -- the government dragging its feet in order to punish the defendant with the process.
I would think that if Merchan denies a motion to dismiss, that would be grounds for an immediate appeal before making the defendant put on a defense that is unnecessary.
-PJ