He lived in a dorm owned and operated by Virginia Tech. Technically, Virginia Tech was his landlord. They could have gone in at any time.
Actually, the U.S Supreme Court has ruled that dorms, along with high school lockers, come with an expectation of privacy the triggers the protection of the Fourth Amendment, making random, warrantless searches illegal. The landlord at Virginia Tech is the state of Virginia, which creates a different releationship than a private landlord would have with its tenants.