But yet, we who do follow Christ was also warned by Him, “he who is without sin, cast the first stone.” So it goes both ways.
However, in this case, Fr Keneally's fault was not secret: he published open slanders against the Church and against his own bishop. And correcting him is not "unnecessary" --- Bishop Paprocki has a right to be defended from Fr. Keneally's falsehoods.
Finally, Fr. Keneally has no good name to save: he has trashed it himself, by his flagrant undermining of Catholic faith and morals.
Telling the truth about somebody is not the same as casting a stone. It is necessary lest others be led astray.
One should be careful how one states it, however; and when; and to whom.