No backdoor this time, but a private (!) key.

No idea what the private key is used for, but doesn't look like you can use it to log into the device.

Private key would be used to decrypt traffic, most likely. (if we're speculating about malicious use possibilities)

No reality is usually boring. It came from an opensource github repo. It was an oversight.

Dial down the conspiracy-factor brother.

If the dial of conspiracy was turned to low for the last few years, it's quickly moving into the hot position.

Often is not the same as usually.