Not sure why so many can't understand the issue here. Canada Post has the right to not honour delivery commitments, which makes their service by default Regular Parcel. They simply cannot still continue advertising and selling services that they do not deliver:
https://www.canadapost.ca/cpc/en/bus...expedited.page
https://www.canadapost.ca/cpc/en/bus...presspost.page
Well, it's a moot point anyway, since IRG didn't answer my question, and I can't submit the request since I'm not the sender.