According to British Airways call center, they dint have any restrictions in place from air lines perspective and all they are saying is as long as passengers fall under the exemption category to enter Canada , they will allow to board.
This is how it should be, arriving country should dictate the terms but I heard few airlines (Lufthansa/KLM) dint allow passengers due to various reasons even though they are eligible to travel
British Airways planning to operate 4 flights b/w London and India
https://www.newindianexpress.com/nation/2020/aug/08/british-airways-to-operate-multiple-weekly-flights-between-india-and-london-from-august-17-2180610.html
it clearly mentioned "
British Airways will be able to take all customers eligible under the guidelines issued by the Ministry of Home Affairs nonstop to London and beyond on British Airways' current flight network"
Hopefully they operate without any issue and allow COPR holders and other immediate family members falling under the exemption