Personally, I find all the lawyerly attempts to rescue the idea that government authority is illegitimate unless it derives from consent rather precious.
First, it is the very nature of legitimate authority that the commands it issues are legitimate independent of the consent of those commanded. A command with morally binding authority isn't a call for volunteers. If we want to draw on how God has modeled the nature of authority, we can look to the fact that the ten commandments aren't ten suggestions. And the fact that the Israelites wanted a king (and God gave them what they wanted, good and hard) doesn't imply that governance under the Judges was illegitimate. (The incident may say something about the prudence of republican subsidiarity, or what today we might call federalism, though).
Second, however one wants to construe this incoherent principle (incoherent principles can be construed pretty much any way you want, which is part of why they find their way into the basis of legal arguments so often: if you can keep the incoherence from being obvious, you can make an argument for anything you like) -- however one wants to construe this incoherent principle, if (for example) the reign of St. Louis IX was "government by the consent of the governed" every bit as much as modern liberal regimes are, then the principle is vacuous.
Why such a vacuous principle should give the warm fuzzies to right-liberals is a bit of a mystery to me. Perhaps they feel that our own Republic must be illegitimate if this foundational Jeffersonian idea - the (incoherent) idea that government powers are unjust to the extent they do not derive from consent - is wrong. I have no idea why that should be the case, unless their notion of legitimate authority is that a present-day authority cannot be just unless the nation's founders were right about everything in their political theory.
So anyway, modern Catholic consent-idolaters can pick their poison: either your principle is so vacuous that it entails no constraints which are not already encompassed by the fact that government's just powers derive from the common good, or all those previous illiberal governments acknowledged as legitimate by saints and even run by saints were illegitimate.
With apologies to the Lost Boys, that's one thing I never could stomach about the Internet: all the damn lawyers.