Some members of the SpaceX software team run an AMA on Reddit just after the Demo-2 flight.
Two members of the team specifically represents cybersecurity (Jeff Dexter) and fault tolerance and safety (Wendy Shimata) but there is understandably not much on cybersecurity in this AMA (ITAR and general prudence preventing it).
The whole thread is on Reddit r/spacex and I have extracted some quotes after the break.