I agree that he doesn't really seem like a person who could do such thing, but it doesn't make Lena who accepts what Stan tells her without checking any less naive. I think it's one spot where Louise scoffing at her for blind compliance and just accepting the deal that she was no part of, isn't entirely unwarranted.
I am sorry, blackmail? Like who? Why? Hello? I don't understand...Lena and Louise are free to ask the landlord themselves and Stans cover would be blown immediatly.
I really don't see much value discussing this. Increasing rents add to Lenas financial struggle and the overarching effect urbanism has on the people. To have this plot point as a scheme for Stan magically becoming a blackmailer just goes nowhere.