Power-seeking corruption (in contrast to its milder cousin, the solely money-seeking kind à la Menendez) exists at the intersection of fraud at its worst and free speech at its most critical.
Let's be clear: what Giuliani et al got up to was fraud. But it's fraud that corrodes not only the economic superstructure of a society, which is replaceable, companies go bankrupt, but also its base metal. So in terms of danger, it's of paramount concern. (How to contain fraud in pursuit of power is almost a defining characteristic of political systems.)
On the other hand, if there is one type of speech free speech yearns to protect, it's the political kind. The kind used in the pursuit (and maintenance) of power.
America has one of the strictest, some would say extreme (I wouldn't), interpretations of free speech. Both in law and custom. We also have a long tradition of resisting the sort of authoritarian populism this brand of corruption finds fertile ground. Private enforcement through civil remedies would be a uniquely American way to balance the problem.
