The GP didn’t mention a lease so I assumed it was month to month, in which case the landlord terminated the lease and the renter moves out.
If they had a longer lease, then I’d agree the landlord can’t force them out before the lease ends.
Rent control throws a wrench in this simple model. In Berkeley, the tenant almost exclusively has the right to terminate the tenancy. Expiration of lease or month-to-month term is not actually grounds for the owner to terminate the tenancy.