Sorry, but your post is ridiculous. It's not the fault of the Minutemen if, per your hypothetical, an elderly person didn't know what he was donating to. This particular organization has made its purposes quite clear. Simcox said from the very beginning that the point of the fence project is to put extra pressure on the President to get his act together. You couldn't ask for a clearer stated objective.
Americans aren't so dumb as your post supposes. No one donating to the Minutemen expects civilians to now take over the role of the President to secure our borders. They know that at this stage, it is a symbolic gesture meant to get the President's attention.
Of course, the longer it takes for the President to act, the more you're going to see frustrated Americans willing to donate and volunteer to build fence and watch the border themselves. Perhaps after a few more years of negligence, Americans who want to preserve this country will seriously take border security into their own hands and build a fence at great personal sacrifice, as our Founding Fathers would.
Liberty-loving Americans have shown that can-do ability from the beginning.
A donor with any sense wouldn't donate to an organization that isn't clear on its tax status, won't make its financial data public, and doesn't have any clear results to show.