If The Official Story Is True, Why Hasn't Gov't Sued?

I haven´t bought any DVD or book from any of those “truther movements”, but I think a clue for what you´re asking might be in the “disclaimer”.
If there is a disclaimer in the “document” then that might keep the authors safe from a suit.
Also, I agree that the Gov. would only benefit those people if they brought up a suit against them.
And if an individual or a group as you suggest brings the suit against them then it will be the same thing, they will say that the Gov. is using you to damage them.