You're worrying for nothing, IRCC will not penalize you for an occurrence which is out of your control.
They have already specified the basis by which the review will be conducted: validity of security and criminality checks and your medical.
Worse case scenario, you may need to get another PCC and medical done, but after you'll get re-issued your COPR. They have not mentioned eligibility at all, because you have already passed that in order to obtain your COPR. They are not reassessing that.
Don't panic.
They will not penalize people who cannot travel due to a lockdown.
your point very valid. however , cannot travel is very subjective.
MOST COUNTRIES including India , have limitations only on receiving flights , not on boarding flights to outside the country.
some people landed in the lest few days using COPRs despite the ban.
straight technically speaking most of us can land !!!!.
but if you looked at it in terms of : housing , jobs , quarantine , shut down in Canada and the ability to return back home in the near future , it will be a very difficult situation to land at that time. the big question : this will be considered and extensions issued ???
or only people from countries that literally shut down the airport , like Kuwait ,Peru , etc ???