Egypt and states surrounding Qatar have banned flights to and from Qatar – and overflights from Qatar Airways.
While I cannot pretend to understand the mind of states such as Saudi Arabia, they cite support for extremist Islamist groups, and funding of terrorism, by Qatar.
BA is already in a very close association with Qatar Airways – which now finds itself with aircraft and flight crews to spare. So, in order to defeat the unions, who are about to strike against them, BA have sought permission from the government to use Qatar Airways aircraft – supplied fully crewed.
The government was quick to agree. It seems that, for them, fighting unions is more important than fighting terrorism.