Smart Locks read data from a Blockchain address instead of an inbound connection. It means a Smart Lock can benefit from the same security as Blockchain itself, protecting both the network and whatever a lock is securing.
The crucial advantage of a Blockchain-enabled Smart Lock is that there is no direct communication between a user and a Smart Lock. The user communicates with the Blockchain only, and the Smart Lock subsequently reads the user instructions. This advantage provides an enormous security boost because a READ-only IoT device is much safer than a READ/WRITE one.