So the pedophile was willing to leave if left in “good standing” but was unwilling to leave if not? And The Vatican was insisting on keeping him because of his transgressions?
Here in lies something that is not really thought out well by many at large. A priest is found to have a credible accusations and my even be charged but put on probation. So the public says, "Defrock him", Bishop. Yet many Bishops don't. On the face of it, it seems wrong but what is better to do? Defrock him, let the accused priest/religious go into the world unabated or to keep him in a place where his contact with potential victims would be limited (usually in a house in a religious order or some other penitential place).
We know that secular society isn't going to care where this person is (as proven over and over again in the papers and on TV) and their chance of corrupting someone again is greater than if they are kept in a location where they are supervised and kept in the priesthood/religious life where they must honor their vow of obedience.
You are still missing the point. Bishop Cummins should have initiated a trial and after a finding of guilt imposed the penalty of loss of the clerical state whether on not Keisle was willing. Rome was not making any ruling on a possible imposition of a penalty by Bishop Cummins. There was no reason for this to go to Rome. Rome's response was to deny a petition for a privilege that would have left Keisle in good standing and relieved him of the demands of celibacy.