There is little prospect of anyone being prosecuted for 9/11 because it was government policy to facilitate the attack for purposes similar to Pear Harbour. In other words it was a political decision not a legal one (as with proroguing of Parliament and declaring war) and in a democracy you can’t punish leaders for war crimes, because democracy requires a peaceful transfer of power to work, and leaders facing prosecution wont surrender power. Only leaders of vanquished nations get prosecuted.
However eventually truth works its way into the political mainstream and those elected by a knowing electorate change policy accordingly, hence why you got Trump, Brexit and Corbyn.