That comment was downvoted for engaging in a tired debate which had already been resolved to everyone else's satisfaction. The prior for "The U.S. government will intentionally murder thousands of its own citizens in a fake terrorist attack" is very low; the abundant evidence (including hundreds of eyewitnesses) that, y'know, planes crashed into the towers makes it even more unlikely. One piece of cherry-picked evidence against the obvious facts was obviously insufficient to change anyone's opinion (furthermore, it wasn't even the point of the post), so it was downvoted.

For the same reason, I downvote "evidence" presented for various religions. The issue has been decided; no given piece of evidence is going to change anyone's opinion, and rehashing the issue is a waste of everyone's time. Political incorrectness has nothing to do with it.