Your Problem, Not Mine
According to RentPrep, landlords are responsible for the pest control of their properties unless it’s contractually stipulated otherwise. Some landlords, however, have a talent for ignoring their responsibilities (and their tenants’ problems) in the most patronizing way.
While he surely understood one of his tenants was dealing with a rat infestation, this particular landlord decided to play it cool and act bossy—as some landlords tend to do. His Machiaevelic plan involves seeing the rats as “pets,” so the tenant is forced to deal with them.