Is it time to start calling out bad cyclists?

Dismounting and walking is possibly OK, that's a slight grey area from what I remember.

The offence is something along the lines of: "propelling a vehicle across the stop line whilst the light is on red". So the ambiguity is whether dismounting and pushing the bike is still propelling it across the line, likewise lifting it and carrying it over. Until it goes to court and is challenged there is no official answer. The subsequent crossing of the junction could also be seen as dangerous or inconsiderate cycling (or whatever that offence is) depending on whether the junction was busy (with pedestrians or other road users).

I've dismounted and walked across the line several times in front of the police. Once was right in front of two police motorcyclists at an empty pedestrian crossing. They never said a word.

I've seen the Police do nothing as someone drove past blatantly using a mobile phone. Doesn't mean it's legal.