One was followed by police while he was in country, then detained by customs officials (I assume it was MSS) on exit, and was told in no uncertain terms not to come back. This is a regular cybersecurity person who was there to speak at a conference. He was given no records and when his company tried to dig into why he was detained, they unsurprisingly had no records of him being detained or questioned.
I also done incident response for a number of companies targeted by Chinese state sponsored actors going after industrial and financial IP.
You keep calling them spies, but in both cases it's not as clear as you make it out to be and there is no evidence they were spying. The US provides quite a bit of information when they charge someone with espionage. Kicking someone out of your country for taking photos of sensitive sites (US) and keeping quiet about sources/methods is different than arresting someone while refusing to show evidence of their crime(PRC).
You act like someone with a regional interest will always be a spy if they have done intelligence work... there are tens of thousands of people who work for intelligence agencies in Canada and many more former employees.
I'm not even denying they might have been spying or providing trip reports afterwards, but without evidence I have a choice between believing the Canadian government or the Chinese government... I'll choose to believe the Canadian government.