My eye went straight to it as well but more because I had passively (embarrassingly) assumed that Plan9 didn't have non-western fonts by default. 'twas a silly thought.
At least Plan9 did something wrong. UTF8 is so superior to this silly 16bits encoding.
Yes, and that's why they (Rob Pike & ken) created UTF-8 and converted Plan9 to use it.
https://en.wikipedia.org/wiki/PythagoraSwitch
I'm not sure why it was there... But just in case you wondered.