They can impose the ban for any university-related purposes (conferences, field-work, collaboration etc). This fall I am teaching, albeit remotely, so while I could conceivably go to the EU as an Irish citizen and teach via ZOOM from there, I'd need my passport to arrive first and the Irish office -- where my PP was literally a day or 2 from being sent out when they closed last November -- is not going to reopen to get my PP just because I'd like to teach from Ourense or Ponferrada or Vigo. That does not count as "urgent business".
I have a sabbatical coming in January, and my hope was to associate as a visiting scholar with one of the universities in any of the above locations, take a Spanish course there, and do some more work on the ground on my secondary research track -- which is on the relationship of foodways to cultural well-being and health, broadly defined. My primary research is about disability, bioethics, and medicine as an institution. Contrary to public perception, sabbaticals are not time to faff around doing nothing; I have to have a research proposal that the university approves. "I'm going to Spain to walk around and eat tapas, visit churches and museums and walk my butt off" does not count. And, for the foreseeable, using the "vacation" card is not permitted by our border agents. So...
As soon as I try to accomplish that, I'm on "university business" and that is banned.
The travel ban is perfectly legal in a public health context that has restricted travel for all Canadians. It is considered an emergency measure.
My emotional response to it is twofold: I mourn the life and opportunities we have all lost to this scourge (and I recognize that I've not suffered at anything like the level that my students have; many come from groups that the virus has been able to target. 10% of my students have become sick; many have lost immediate family; some are now the only earners for their families; some are fighting with younger siblings for access to the *one* computer in the family...). But I also recognize that I have no particular entitlement to wander the world to please myself, and so I have put some of my toys away (no cruising flight booking sites, muted Booking.com, etc).
Eventually this will end... my PP will arrive, and perhaps by then I will be in the early exit plan to retirement with a gradually diminishing amount of teaching to do over 3 years to a final exit when I am 57/58... and then I can move to Spain. For these opportunities I count myself among the very fortunate.