I imagine he was using the insurance reason as way to be nice to tell you he does not want to. I am sure they have dealer plates that they use when people testdrive cars. With the dealer plate comes insurance that covers anybody driving the car. Would be no different than him allowing somebody to testdrive a car for purchase.
I imagine he is letting you down and trying to be nice about it not because he does not like you or something as musch as the damage you could do on the car trying to learn. Some people pick it up real quick and others it takes a while to catch on. You could easily burn through a clutch trying to get the hang of it. If this were to happen it could be costly to him in repairs.
Do like everybody else and go to a lot and testdrive a stick. Or go to a car rental and rent one. This will give you a quick idea if you are going to get the hang of it or not. I am sure you have a friend that has some old beater that is a stick that they would let you try in.
Whatever you do good luck at learning!
