yekke – without reading everything i do know that if the askan publicly humiliated the talmid chocham, someone who witnessed it was allowed to tell you about it. When someone does aveiros in public their status changes.
Secondly, if someone tells you that a person wants to kill you (or cheat you or rob you etc) you are NOT allowed to be mekabel but you ARE obligated to be cautious, and look for signs with the understanding that it might be for no reason but that it might be true.