>A friend of mine from childhood became a top expert in formal verification, and got a contract many years back to help Airbus perform formal verification on their control software. I don't know many details, but according to my friend's father, he would never fly on an Airbus jet after this experience.

There are safety anecdotes about all of the major airplane manafacturers. If Airbuses were actually unsafe, they would crash more often.

>who told them to take a hammer to certain fuses or breakers

There would be an incident report about this if it happened. No need to rely on your friend's story.