I'll say this kind of publication with a bunch of specific (And possibly contradictory) rules is always a bad idea, without some documented reasoning and goal.

It sounds to me like what they are trying to convey is that they don't want you leaving the secure side of the airport. Canada historically hasn't had "sterile" transit, and usual customs & immigration rules apply for transiting PAX. An exception was made early in COVID times for testing/vac status.

You can ask whoever you want and get whatever answer you want, but ultimately this is going to come down to an individual border agent at some point.