I wonder, David, what you would have written if the Pope HAD accepted the resignations. Would you have criticised his decision? I doubt it. No, I think you would have praised his decision and cited it as an example of how the Pope is taking a tough stand on the abuse issue. But unfortunately, the Pope didn't accept the resignations and didn't even bother explaining why. So you had to try to find some positive explanation.
In my view, there is the issue of honor and decency. If Bishop Moriarty had the decency to go because he did nothing to challenge the culture of secrecy, then these bishops should also have the same decency as they didn't challenge it either. That's the bottom line. Also, what would Jesus or the apostles have done? Think about that, and not legal hair-splitting about who was actually mentioned in the Murphy Report or not.