Likely involves their most senior devs bypassing normal deployment procedures / access controls. In this case, to be able to edit their live production environment instance instead relying on Workers KV / other impacted internal services (which a lot of their infrastructure relies on) Which would then enable a proper rollback. The aim being to restore service as quickly as possible to minimize the customer impact.
Working with some large companies this sounds likely. They'll typically have all changes occur in a testing environment and get pushed to prod via automation.
I assume when they said that they mean a hacky, manual, editing config files means of redirecting traffic.