This is because what Corsi is peddling is nuts and people like Hannity, Beck, Malkin, Levin, etc, etc, etc, want absolutely nothing to do with this conspiracy nonsense. Meanwhile Corsi is taking crazy to whole new heights. On Alex Jones show he is now claiming Donald Trump was in on the whole conspiracy. And now Corsi is telling us smiley faces on the birth certificate are some kind of Da Vinci Code.
The left image is from the WH PDF. Middle was high res released by AP. Right is Guthrie's low res snap. I think there were two uses of the same rubber stamp with a slightly flawed A, perhaps less ink on the white background form. This theory requires that two copies were brought from HI and one of those (the AP in the middle above) was printed on plain paper (no green hashes). The left image could easily have been altered since we know the image was manipulated at the WH. The middle one could have been altered and/or manipulated, but we won't know since AP only released a JPG scan.