Sirius
What are you on about? Remus was brought in because the bookshop is across the street from Fortescue's. Same as Ollivander, Madame Malkin, the manager of Flourish and Blotts, and all other business owners who came in. They were free to leave whenever they wanted. None of them did, because they give a shit about their community. Remus included.
Stop trying to mould the real world into that one inside your head. You sound like an angry little boy.