This is one of the best (if not the best) explanations on how to troubleshoot 2 wire busses. I worked for years as an Avionics Tech and more years as a control tech on DDC systems. 2 thumbs up!
Since I worked on brand new aircraft, I had very little reason to use a Megger during trouble shooting. The wire insulation was new, so high impedance shorts were very rare. Very sorry about that.