Unfortunately, because the zooming is rather fast, it is easy to miss the rest of the sentence, so as you correctly note, some viewers got an incorrect impression. It would have been fair for Moore to point out this possible misinterpretation on his website. However, the claim of deliberate distortion is ludicrous for several reasons: a) Moore clearly states that "before he came to Flint", Heston gave an interview. In the excerpt from said interview, we can see that it is from March. If Moore wanted to deceive his viewers, why would he say this, and show the month the interview was published? b) Why should Moore leave the words "Clinton is on the Today Show" visible in the text, which is necessary to correctly interpret the highlighted part? I reviewed the sequence several times and it is perfectly possible to see this text without pausing. c) Both the "soccer mom" interview and the sequences showing the NRA rally make no effort to distort the fact that this rally happened months after the fact. The camera lingers on Bush/Cheney posters, and the protestor is quoted as saying that "we wanted to let the NRA know that we haven't forgotten about Kayla Rolland". You make the hysterical claim that the interview "may be faked" (on the basis that no name is shown for the interviewee), but if Moore had faked it, why the hell should he put this sentence in the protestor's mouth, which directly contradicts the conclusion that the rally happened hours after Kayla's death? Why did Moore, the masterful deveiver, not edit this sequence out? This makes no sense. Opinions may vary on how tasteless it was for Heston to hold a pro gun rally on the location of the nation's youngest school shooting months after the fact, but this sequence of "Bowling" is without doubt the most unfair to Heston. The claims of deliberate distortion don't hold up when viewing the whole scene, though -- as "Hanlon's Razor" states, one should never attribute to malice what can be attributed to incompetence. The somewhat inept editing of the NRA press release has led some viewers to wrong conclusions, which is unfortunate, but Moore's critics have no interest in viewing the matter fairly. Had they done so, Moore himself would probably have apologized for the gaffe. In any case, at no point does Moore make a false statement, in contradiction to claims by critics that his documentary is "full of lies". 
When did Heston give an interview?
March