Spirit Aerosystems also does work for Airbus.
-- Spirit Aerosystems 2022 10-K filing
They do 3 times as much business with Boeing than Airbus.
(Airbus may also wrap Spirit in their own Q/A process to mitigate the issues, which Boeing is certainly lacking)
https://viewfromthewing.com/boeing-whistleblower-production-...
The worry is that Airbus is ALSO going to be affected by this shitty quality, not that Boeing isn't totally fucked by its outsourcing to Spirit Aerosystems.