I don't see how it's comparable to holocaust denial. But 9/11 conspiracy theories are pretty silly. People get so invested in them and it's just like, dude! The same government is putting people in jail to be raped and brutalized for having a certain kind of vegetation. You don't need 9/11 to prove that the government is disgusting. The metaphor I like to use is it's like you're prosecuting this serial killer and ou have video evidence where he holds up his id, states his name, then proceeds to murder 90 people on film, turns himself in, the DNA has been matched up, there are 100 eye-witnesses, and you choose to base your case around... the possibility that he may have jay walked in 1992, causing a fender bender. If you want to prove that the government is evil, there's plenty that they freely admit to. Torture, rape, murder, kidnapping, etc. You don't need to prove they were behind 9/11. That's my message to people who are conspiracy inclined anyway.