Fresh concept for an ice-based lock without keys

I had a no-keys-required ice lock concept I wanted to share. It seems straightforward enough to construct using basic components. This is just a preliminary sketch; I haven’t built it yet, and I’m unsure about its safety and reliability. The setup involves tying a rope to a steel rod that slides inside two sections of PVC pipe. The rod sits atop a pile of ice cubes within the bottom section. As the ice melts away, the rod will eventually fall to the base, instantly freeing the rope. It could work well for self-restraint against a wall.