In 2011, this was considered a high-security feature. Today, it is less secure than modern alternatives. Swipe sensors create a lower-resolution image compared to modern capacitive or ultrasonic sensors. While sufficient for keeping casual snoops out of a laptop, it lacks the sophistication of modern biometrics.
Here are some detailed specifications of the Broadcom USB Swipe Sensor E6420:
This is where the device shows its age.
This article explains what this component was, how it worked, and why it matters for vintage laptop enthusiasts today.