Why "U.S. Citizen?" Why not "U.S. Citizen or permanent resident?"
I e-mailed the organizers of the scholarship to ask the question, and they promptly responded that, on reflection, permanent residents should be included. The revised Blogging Scholarship page reflects this.
I should say, by the way, that my e-mail to the organizers didn't condemn their original position, nor do I condemn it now -- if Americans want to give gifts to Americans but not citizens of other nations, that's fine by me. But changing the program to also consider our nation's long-term guests (many of whom will become citizens, and many more of whom are likely to contribute to American life) also strikes me as a fine and hospitable position.