AC.com has a longer list of eligible passengers:
Which is good news for me as a UK citizen with Global Entry - and, indeed, I have an e-mail from the Global Entry scheme stating I'm eligible for TSA Pre.
However, my next trip on AC will leave the US from SFO, where participation is on a 'select time basis' only.
Air Canada Altitude, are you able to clarify when you expect this to operate?