you expect it not to ask CC info? Their goal is to make you use it, even after the free credit has expired.
There not scamming but rather preventing it. If you don't submit CC info then they have no idea who you are so if anything illegal ever happens they can't pin you down. With CC info they can. Plus its a service that is spose to make money for them. If you are not going to be bothered entering CC info then how do they make anything off you?