The reason is to fool town. TAC is fully aware of the flavor here and could be using it to his advantage to get away with being open scum. Wolves aren't always going to fake claim a town role.
However, the same doesn't apply to Ratchet since iirc, he said that he doesn't know flavor. But it's because he claims to be Perospero and has a second wincon. Whatever that wincon might be, do you know not agree that it would be pro-mafia? I have zero incentive to let him go when there's reason to believe that he is a pro-mafia indie.
You say that you want to let them go and lynch others right? Who are those others?