No, actually, you are wrong. They did want to ensure that every State had a Republican form of government. They distrusted a democracy as much as a monarchy.
But would they send an army in to depose a democratic (as opposed to republican) government? I’m inclined to doubt that. How would they define a democratic government that was beyond the pale? What exactly constitutes a republican government? What if that government doesn’t meet your (and their) definition of a republic, but it is supported by a clear majority of the people of the state? It’s not as easy as it appears to come up with a clear definition.
Now a restoration of King George in (pick a state)... Same with a Cromwellian dictatorship.