Now, as to seeking justice for the removal of President Zife, the process was ugly but that seemed to be the intent — as we seek a more perfect union, we often have to face demons of our own creation. What you're advocating, in part, was discussed by the characters in the several novels that addressed the issue and was reluctantly dismissed for the key reason it was nearly universally agreed that the Klingons would wage a ruinous, honor-fueled war of vengeance with the Federation, especially because the Federation would almost certainly refuse to surrender Zife to the Klingons for justice. IIRC, Captain Picard and the rest of the Enterprise crew reluctantly accepted this reality and kept their piece.
Consider the full ramifications of what may have happened based on further stories: If the Federation and the Klingons went to war, they would be extremely weakened by the time the Borg invasion was launched in masse. The likelihood of surviving the Borg invasion would have been significantly less — possibly near zero, given the number of separate individual actions that were needed for Alpha and Beta quadrant powers to ultimately prevail against devastating losses.
The specific events that instigated the invasion in "Destiny" may have been different, but the Borg's underlying motivations would've led to an invasion at some point.
Given the situation as the characters knew at the time and given the events to come, is the likely destruction of all non-Borg life in the galaxy worth bringing Zife to justice via proper channels (and later the conspirators that removed an obvious cancer from leadership)? Many American leaders and jurists have noted that the U.S. Constitution is not a suicide pact
and that the duty to self-preservation can be higher than the strict adherence to what is referred to the highest law in the land. Consider President Gerald Ford's pardoning of his predecessor Richard Nixon. Nixon had resigned and was out of power, but further pursuit of justice could have fractured the country further.
Yes, Min Zife's removal was extralegal, but as other characters noted, the succession process was carried out following what we know about the Articles of Federation. When Bacco learned of Ross' involvement in her predecessor's removal, he was pressed into retirement to remove his influence on the administration.
That was the condition sought by Seeker reporter Ozla Graniv, who was able to gain leverage on the Bacco administration by bluffing
. I don't know if the Bacco administration would confirm her findings on the record (but they wouldn't stop her either). That's key — Graniv couldn't publish what she had because the Orion Syndicate would kill her for publishing the information they provided her without attributing it to another group. Graniv's decision is another difficult between doing what is truthful and right and preserving the union and most of the ideals of which it stands.
I agree it is an imperfect solution, but as many Trek authors and Otto von Bismarck keep trying to tell us, politics is the art of the possible