Is it time to start calling out bad cyclists?

Don't tell me you've never had anyone have a go at you for something, especially a stranger, and initially thought they were a twat and even told them so, then later grudgingly realising they were right?

That's a good point.
But as the Samaritan in your example, I really find it unpleasant to be told to eff off by people in the wrong.
It could really ruin a nice ride. My philanthropy can only go so far.

So in answer to the OP, no.
(Other than shouting, "RED"; that's a given.)