Jury nullification is almost impossible. One juror taking an activist stand likely could not control an entire jury. The juror could only be a holdout resulting in a hung jury. But suppose a juror did. Say the juror did not believe that assaulting a police officer should be a crime. Clearly the evidence showed that
The defendant committed the crime, but an activist juror did not believe that assault should even be prosecuted. That one juror convinced the rest of the jurors to take a moral stand and let the assailant go.
The judge in deciding that no part of the evidence supports the jury verdict would simply enter "Judgment Notwithstanding The Verdict". All over. Jury verdict thrown out.