(4) Except pursuant to subsection (2)(a) of this section, this section shall not be construed to require structural changes, modifications, or additions to make facilities accessible to a person with a disability except as otherwise required by law. Nothing in this section affects the rights, responsibilities, and remedies of landlords and tenants pursuant to chapter 59.18 or 59.20 RCW, including the right to post and enforce reasonable rules of conduct and safety for all tenants and their guests, provided that chapters 59.18 and 59.20 RCW are only affected to the extent they are inconsistent with the nondiscrimination requirements of this chapter. Nothing in this section limits the applicability of any reasonable federal, state, or local restrictions regarding the maximum number of occupants permitted to occupy a dwelling.