I don't understand the Bush song situation completely, so maybe I am incorrect, but the cut and paste above sounds like it was a group of children put together to sing a song at an event -kids from various places, and we're not sure how they were selected, etc.

I don't think it's splitting hairs to say that there is a difference between a group of children who tried out for a spot in a private 'chorus' that is singing for an event and school children having a teacher use that as part of her curriculum. I think parents are free to indoctrinate their children politically if that's what they choose to do, but I don't think the school should take on that role. If the kids at the White House were there as a result of their families arranging for them to be part of that performance, that is okay by me. But it wouldn't be okay for a tax-supported school system to promote a politician through and to the students.