I suppose if you believe the US government is the personification of liberal democracy, then NED would be a beneficial tool.  How long do you expect the US to embrace liberal democracy?  Not long ago, that assumption was clearly not the case overseas in such places as Guatemala and Iran, though - granted - that military force was indeed used in those cases.  Are those days definitely behind us?  If you say yes, history may yet prove you wrong.

From another angle, I would argue that there is something of a parallel here with the Supreme Court's ruling in Citizens United v. Federal Election Commission in 2010, upholding the rights of corporations to make political expenditures under the First Amendment.  While that is obviously a domestic affair involving the US constitution, I believe the same principle might be extended abroad concerning NED's activities (at the same time giving rise to similar reasonable objections as expressed in the domestic case).  If, for the sake of argument, Chevron is destroying the Ecuadorian rain forest and the government in power is threatening to expropriate their holdings, would it be a victory for liberal democracy for NED to engineer a defeat of that government (involving perhaps a completely different issue where the government has occasioned misdeeds) and it's replacement by one favorable to Chevron's continuation in the country?  Perhaps the government indeed deserved to lose the election, but whose interests are ultimately being served?  One might be skeptical in this day and age where there is a growing confluence of corporate and government interests.

"Beware of the man who does not talk, and the dog that does not bark." Cheyenne