I'm not so sure the reason is that Berg didn't trash the US, my guess is that Moore didn't use the film because Berg was not really a Bush supporter. There is something very strange about who Berg really was, possible connections with Prometheus radio, a George Soros project and just a lot of unanswered questions. Just the fact that Berg's father calls him a Bush supporter doesn't make it so.
"Prometheus radio, a George Soros project"
No, just his antenna repair company, no Soros connection.
I had forgtten that George Soros is a backer of Prometheus Radio!!!! What a tangled web Michal Moore, Geroge Soros, Michael Berg...and all the lefties have woven.