While I agree that medical device safety includes reliability, safety and reliability overlap in a significant way, but a reliable device may not always be safe, and a safe device may not always be reliable.
For example, the device may be designed to fail safely in use, but fail often i.e., safe and unreliable. And a device may be very reliable, but in use expose the user to high risks i.e., reliable and unsafe.
While I agree that medical device safety includes reliability, safety and reliability overlap in a significant way, but a reliable device may not always be safe, and a safe device may not always be reliable.
For example, the device may be designed to fail safely in use, but fail often i.e., safe and unreliable. And a device may be very reliable, but in use expose the user to high risks i.e., reliable and unsafe.