Unlike your "I suspect the Germanwings aircraft did not have a physical "deadbolt" fitted, so that's another red herring.
Pure supposition on your behalf.
No, not pure supposition - based on 20+ years' experience of flying Airbuses around Europe - how about you? It's clear that nobody on here is going to reveal whether the aircraft had this security feature (fair enough - I wouldn't if I knew the answer) but that's the point - we don't even know what security features were fitted and what emergency options were used/available, yet somehow within a few days of the crash it's done and dusted by some on here. There are a lot of options, with multiple airline selectable options, and I'll bet if you asked all of that crew what they were you'd get 6 different answers, as pretty much any European A320 Captain would if you ask that in the security brief when you next go flying. Try it ...