Yeah, not really sure how a globally distributed manufacturing operation with a complex supply chain and customers all over the world that need access to data for their operations is supposed to function effectively without it.
(and I say that as someone that used to sell commercial aviation data that came on CDs...)
I'm not sure what the 'critical' stuff is either or what the details of Airbus' network hosting and knowledge compartmentalization strategy is, but you're not going to run a globally distributed manufacturing business with complex supply and maintenance requirements without having technical specs, CAD files, diagnostic criteria customer records etc sitting on computers connected to the internet.
(and I say that as someone that used to sell commercial aviation data that came on CDs...)