"It's not something I'd want to do at this time, but if I change my mind, I'll get back to you."
No discussions about the legalities of the matter.
In other words, you're politely saying 'No.' If they try to press the matter, simply say, "I'm sorry brother, I did say 'no,' but I'll get back to you if I change my mind."
Or.............."I'll take the form and give it some thought." Then, if approached again, "I gave it some thought and decided that it's not something I'd want to do at the moment. If I change my mind, I can get back to you."