I hate to defend the KGBO, but I don't think this one is their fault. AODA requirements came in 1/1/21, and I don't think there is a way to make the pdfs comply. If it doesn't comply for everyone, it cant be available for anyone. That's the rule, as silly as it is.
According to Ontario.ca, "Beginning January 1, 2021, all public websites and web content posted after January 1, 2012 [nb: I suspect a typo here and it s/b 2021] must meet WCAB 2.0 Level AA." According to Adobe website, "PDF documents can be made to meet WCAG 2.0 to the Priority AA level."
It would appear then that LCBO simply doesn't care and took the easy way out eliminating the problem by making the PDF's disappear.