From the article: “The flight they had difficulties boarding was a British Airways flight.... ...Effectively, in these situations the ticket issuing carrier (here Air Canada) acts as an agent for British Airways selling the ticket. But British Airways alone is responsible for providing the transport. That said, our agent did contact British Airways on three occasions to assist this family while they were attempting to use their ticket out of Tehran but was unable to help them resolve the matter.”
I'm sure some twisted mind here might dream of Air Canada returning the favor. Like to somebody with a BA ticket, stuck in Goose Bay...