The receiver could always reencrypt (and usually does, IIUC; signaling this is the point of the "repeater bit" in the protocol). If it was just a dumb passthro

The receiver could always reencrypt (and usually does, IIUC; signaling this is the point of the "repeater bit" in the protocol). If it was just a dumb passthrough, then there wouldn't be much need to advertise HDCP compatibility in the first place.