Because that is what the law says. Those who make claims otherwise will not find any support in the courts.
1. The courts will not rule on NBC because its only required of the President and the Constitution only allows it to be contested in the Electoral College and in Congress. This is why all of the court cases against Zero have been thrown out under the grounds “Plaintiff has no standing.”
2. The following posts provide, in detail, why he is not eligible:
http://www.freerepublic.com/focus/f-bloggers/2619619/posts#9
http://www.freerepublic.com/focus/chat/2626433/posts?page=362#362
http://www.freerepublic.com/focus/chat/2626433/posts?page=435#435