Certainly, within what's Good (tm) and Acceptable (tm), funding better education in the third world is the most effective method.

However, if you go far enough outside the Overton window, you don't need credibility, as long as the power asymmetry is big enough. You want food? It only comes with a chemical agent which sterilizes you, similar to Golden Rice. You don't need to accept it, you're free to starve. The failures of colonialism as well as the most recent forays into the middle east stem from the constraints of also having to placate the court of public opinion.

Regardless of this one example, are you taking the position of "the most effective methods are those within the Overton window"? That would be typical, but the actual question would be: Is it because changing the Overton window to include more radical options is too hard, or is it because those more radical options wouldn't feel good?