What's funny is that this poll actually shows surprisingly little support for the idea of a government conspiracy. Only 28% think the government is "mostly lying" about 9/11. Nearly 70% think the government is mostly telling the truth, but may he hiding some things. There is nothing new here.
So, a little lying is okay, and a lotta lying is not?
IMO, a "little" lying shows a coverup. What motive would they have for a coverup? Either to protect the bad guys (which denotes complicitiy), or to hide their mistakes that day (which means they broke the law and have incompetent people and systems in place right now and we're not safe).
Saying it's okay that they're lying about 1 thing is unacceptable, because it means they could be lying about 1000 things.