Legally, can a property owner tell a tenant that certain guests are not allowed on the premises (and enforce this)?

A good friend of mine rents an apartment in a house. The homeowner does not like one of my friend’s guests, and told my friend that this person is “not allowed on the property.” Because my friend is friendly with the homeowner (her landlord) she is not arguing it. I am just curious if this is something that a homeowner could enforce.

Similar scenario, entirely different circumstances: someone else I know got into a heated shouting match at a local municipality’s Public Housing Authority board meeting. He did not get arrested, he was escorted out. He received a letter from that municipality’s Public Housing Authority saying he is banned from all of this municipality’s public housing properties. He is not a tenant, he lives in another town, but he is an activist. His daughter lives in one of the buildings. Is it legal to ban a person from Public Housing property for something like that?