What is the legality surrounding Gus's decision not to rent to smokers?

Gus can choose not to rent to smokers under fair housing laws because smoking is not classified as a protected characteristic under the Fair Housing Act. The act protects certain traits such as race, color, national origin, religion, sex, familial status, and disability. Smoking status does not fall within these categories, allowing landlords the discretion to impose restrictions on smoking in their rental properties.

This decision can also be rooted in health considerations or property maintenance issues, thus permitting Gus to establish a smoke-free environment without violating fair housing regulations. Therefore, his choice is legally permissible and supports the right of property owners to set conditions on their rental agreements that pertain to lifestyle choices unrelated to the protected classes.