Moral judge deeply committed to utilitarianism

I​‌‍‍‍‌‍‍‌‍‌‌‍‍‍‌‍‌‌‌‍​magine a very moral judge deeply committed to utilitarianism. A case comes up in which an innocent (the judge knows this) person stands accused of embezzling the life savings of huge numbers of people. If the judge does not convict and harshly punish the accused, a violent crowd outside will riot and will cause enormous suffering and damage. Should the judge convict the accused, if that conviction maximizes the total pleasure (minus pain) in the world? What is to stop this judge from making a h​‌‍‍‍‌‍‍‌‍‌‌‍‍‍‌‍‌‌‌‍​idden exception to norms of justice on utilitarian grounds?