It does not pass the smell test. This is not an error one would make. Imagine one gets an email from Z, X-Y <xyz...@ucanuckistan.ac.ca>, then why would one describe this as "emails (ed: plural!) from China"?
My theory that fits the evidence given is that the professor is withholding the real "angry emails from China" because she thinks if those are published, then she definitely won't get a travel visum anymore and thus negatively impact her career.
It's possible. It's also possible that this was the only email, but she got a warning from some Chinese government agency through another channel.
There is of course also the distinct possibility that the professor was personally offended by the tweet (or imagined the offense taken) and made up the "emails from china" to make it seems more impactful.
I agree. This take is supported by the fact that the Prof refuses to reveal the email address of the Canadian student. My guess is similar to yours. She received emails e. g. from a Chinese consulate but is not allowed to reveal that fact - so she made up this "Canadian student" story.
Well, you would be surprised. It seems attempting to censor Twitter and other publications is part of their job. They even review German children books:
My theory that fits the evidence given is that the professor is withholding the real "angry emails from China" because she thinks if those are published, then she definitely won't get a travel visum anymore and thus negatively impact her career.