So you claim, of your own authority with no Constitutional warrant. Your so-called "prohibition" exist in your mind, not in the constitutional law of these United States.
The Federal government may conduct foreign policy according to its discretion, and if it decides that assisting a foreign nation in making a transition from non-representative to representative government is a useful policy (such as it pursued in West Germany), it is has the prerogative to pursue such a policy.
Further, the whole notion of democracy was abhorrent to the Founders (and with good reason) and SHOULD be abhorrent to any rational, thinking conservative today.
The notion of an unmixed democracy without separated powers and checks and balances was considered unproductive by our Founders, but they had no problem with the democratic election of the lower house of the legislature.
To my knowledge the US has never promoted the establishment of an unmixed democracy, but rather of representative governments in which the legislature was democratically elected.
Evidently, it existed in the mind of George Washington, too. But what would HE know about constitutional intent?