Mueller tried this before, with his indictment of Russian entities that supposedly supplied Facebook advertising, only to unexpectedly face a defense team hired by one of the entities, Concord Management. His response has been to delay and obfuscate, quite shamefully (dumping four terabytes of untranslated Russian documents in response to discovery requirements), and then pass off the prosecution to "outside prosecutors" so his team can escape accountability for their phony indictment.
In his second round of indictments purely for show, Mueller tried to avoid the danger of a defense being mounted by making the indictments criminal and naming defendants who are real individuals who would face prison if convicted.
Of course, anybody with half a brain would see that once the United States legitimizes criminal indictments of foreign intelligence officers in this way, other nations will apply the same logic to our own intelligence operations. And the former U.S. Ambassador to Russia, Michael McFaul (an Obama appointee) tweeted: