I remember those books quite well. I understand why Picard did what he did -- he honestly felt that Zife's crimes were too vast to allow him to stay in office, but he also genuinely believed that to expose Zife's crimes would be to risk a war with the Klingon Empire that would get billions of people killed. I understand and respect the fact that he took the course of action that he felt least likely to cause so many deaths.
But that doesn't mean that what he did was not a subversion of Federation democracy. It doesn't mean that he did not think he knew better than the people of the Federation. That does not mean it was not still a plot to force the legitimately-elected President out of office at gunpoint.
And I am deeply troubled that neither Picard, nor his co-conspirators, seem to have considered at least two other options: the possibility of publicly exposing Zife's crimes and then the Federation extraditing Zife to Qo'noS to face trial in the Klingon judicial system; or the possibility of disclosing Zife's crimes to the Federation Council, and allowing the democratically-elected Federation Council decide whether or not to impeach Zife.