Michael Moore Tries to Deceive All Of Us

This is an old issue, but I really want to bring it up. It concerns Michael Moore's film Bowling for Columbine.

It has been well-documented that Michael Moore spliced the "from my cold dead hands" speech and the speech given after the Columbine massacre (google it) and tried to make it seem like Heston stood in front of a Columbine audience right after the massacre with his gun yelling "from my cold dead hands". I just read Michael Moore's site where he justifies his actions:

As for the clip preceding the Denver speech, when Heston proclaims "from my cold dead hands," this appears as Heston is being introduced in narration. It is Heston's most well-recognized NRA image – hoisting the rifle overhead as he makes his proclamation, as he has done at virtually every political appearance on behalf of the NRA (before and since Columbine). I have merely re-broadcast an image supplied to us by a Denver TV station, an image which the NRA has itself crafted for the media, or, as one article put it, "the mantra of dedicated gun owners" which they "wear on T-shirts, stamp it on the outside of envelopes, e-mail it on the Internet and sometimes shout it over the phone.". Are they now embarrassed by this sick, repulsive image and the words that accompany it?

The question I have is: how does Michael Moore have people that still believe what he shows in his films? If he had made a mistake, or if someone in his office had maliciously edited the speech without Moore's knowledge I would understand it would make more sense to me. The scene in question is a major part of the movie - and would have been really effective if not for this dishonest error. Charlton Heston waving a gun in the air like a madman would have been a very dramatic way to show the NRA in a bad light.

Another question: does Moore really believe his own explanation? He has to know that the scene is a big lie, which just makes it bad propaganda. The guy deliverately tried to mislead his audience.