You don't find yourself in litigation for the legitimate uses of Tor.
A knife can be used to cut a chicken, it can also be used to kill someone. You would not deny your neighbour when he asks to borrow a knife because "you could kill someone with it".
The risk that your neighbor will use your knife to kill someone is far lower by comparison. Additionally, the risk that there is a legal threat should they choose to do so is also quite low.