No you are not liable for supplying ammo. But you are describing giving ammo to people who have done nothing to prepare. Now you have something they need and you are arming them...
Hey, on cut shells, it is possible for them to come apart in a tube. Not done it myself, but I would think it would be better to spend a little more for some slugs or 00 buck for right now for your HD shotgun. Save the cut shells (at least the widespread use of them) for the SHTF day.