I think the central fact of the Berland Scandal is almost no one emerges unscathed (i.e., righteous).
Without naming names, read this short work (next reworked into this) to see what I mean. Many, many rabbis and others knew what was happening, but they closed their eyes, allowed themselves to be intimidated into silence (or even being photographed with him!), gave ridiculous excuses (such as: “This is an internal Breslov affair” (?!), p. 15 here), and the like.
They themselves admit to knowing the facts for decades (even less justifiable than all the cases of rabbinic ignorance, such as Elior Chen), see here p. 32. Some excused him by just calling him “crazy”, see the last pages of this. Is every Rasha, then, literally crazy?!
The halachos regarding hiding a Torah scholar’s sins were clearly irrelevant from the very beginning because this was no one-time fall. He was spreading Sabbateanism for decades, destroying families in boatloads via divorce and debt, displaying wanton promiscuity, ordering extra-judicial murders, speaking real-life heresy, and so on. Some rabbis knew all that. And then did nothing, except a comment or two to a confidant, not even a whispering campaign. The only thing that pushed them to finally, finally speak out was the outrage of Chushim-ben-Dan-type youngsters.
Now, certain great rabbis still counsel silence… This may have happened with Shabtai Tzvi and the rabbis of Jerusalem, too! Gershom Scholem’s biography (Sabbatai Sevi: The Mystical Messiah, passim) logically hypothesizes their relative silence (not sending copies of their early excommunication pronouncements abroad) greatly enabled Shabtai Tzvi’s movement. Their logic, too, was presumably to refrain from “giving him life” by extra publicity. Yet people assume הואיל והוו יתבי רבנן ולא מחו ביה ש”מ… As Shlomo Hamelech says, don’t be too smart.
Update: I deleted the example of Shalom Arush, who variously pretends he supports or opposes Berland yemach shemo based on who he is speaking with at the time, the snake.