There are a number of mechanisms that operate when it comes to decision making in a group. One of them is that when a dominant leader states an opinion, the majority of the rest of the group tend to agree with that opinion. Once George W. made the pronouncement, “Osama did it” and the news media, notably CNN and Fox News ran that hundreds of times, it was hard for anyone to offer a contrary opinion. Also, at a time when saying anything that could be construed as “Anti-America” was roundly condemned and your job could be on the line for it, those who dissented with the “official version” of events mostly chose to keep silent.
You appear to be pushing the straw man argument hard. It really does not matter how the twin towers and building 7 were demolished. What really matters is why.
Although in late 2001 and for two to three years after that, the majority of Americans were convinced that 9/11 was an act of terrorism, recent polls have found that a majority of Americans now think that their own government had a hand in the events of 9/11. Why would that be the case? Well, since then, the evidence that Bush and Blair flat out lied about Suddam Hussein having WMD and Iraq being involved in 9/11 has become overwhelming. Not only did they lie about it, but they colluded to manufacture evidence to persuade their respective countries’ elected representatives (Congress and Senate in the US, House of Commons in the UK) to vote in favour of attacking Iraq.
Now the majority of Americans have made the connection, and concluded that if Bush could lie about Iraq having WMD and supporting Al Queda, then he probably lied about Osama bin Laden and Al Queda and 9/11 too.
Under these conditions, the White House and the State Department have still not produced solid evidence that 9/11 was an act of terrorism, even though their jobs are now on the line because of that and the lies propogaged about Iraq.