Respectfully, a "ridiculous theory" would be those typically originating from the Left, e.g., "Bush ordered the World Trade Center destroyed so he could impose a fascist dictatorship and build a pipeline through Afghanistan." Prima facia absurdities that would require the complicity of literally thousands of bad actors within the government, without a single whistleblower.
As Franklin said: Three people can keep a secret, so long as two of them are dead.
Several thousand?
That aside, I don't think it ridiculous in the least to imagine a conspiracy amongst a handful of virulently anti-Bush A.N.S.W.E.R. types (Moore definitely included), with the means and the motivation, to engage in a risky operation in advance of their agenda, especially if it stood a chance of undermining the Bush administration.
I'm sure they never saw Berg's murder coming, because they are indeed that naive, but regardless: Never doubt for a moment that Moore and A.N.S.W.E.R. would gladly, in a heartbeat, exchange the slow beheading of every man and woman in a U.S. uniform in Iraq, for the guaranteed removal of George W. Bush from office. If Berg was their cameraman, then in their minds, he died in pursuit of a noble cause, Bush killed him anyway because it was the invasion that led to the murder, and his death won't be in vain, so long as he can be portrayed as an idiot Bush supporter who got what he had coming to him (as opposed to an A.N.S.W.E.R. member, about whom they would assume we would say the same thing - although we wouldn't), and thereby, help end the Bush Presidency.
If this is the case, and I believe it very well may be, the entire Moore charade is about to collapse like the house of cards it has always been. It would be the end of his career as a documentarian. Not only would he have orchestrated a fantastically ill-advised scheme that led to the brutal murder of a naive kid, but he and his cronies - including the boy's own father - engaged in the most shameful assortment of lies and coverups ever foisted upon the American public.
Again: Moore has ample capacity to prove this not to be the case. He need only release this interview. And one way or another, he is going to do so - either willingly, or under subpoena in a federal investigation of a felony murder.
What I don't understand is why Moore never told anybody about this until the article yesterday at Salon.com.
If there is nothing sinister about this, why wouldn't he have called the family and said, "I met with your son, I have video of him, quite possibly the last videos of him, would you like to see it?"