If he'd have slowed, he could have carried on his merry way without coming to a stop
The majority attitude on twitter is
"We're going to do as we please, and if you don't like it, get out of our way. You're the ones who are vulnerable, so you must be stupid for going on the road in the first place.", and the problem with your argument is that it will just create more of this bullying. I could walk round Tescos swinging a baseball bat indiscriminately and tell everyone they're stupid if they don't get out of my way. Nobody wants to get run over, but if you can screech to a halt with your wheel an inch from their door it gets the message over better than endorsing their behaviour by giving way unnoticed.
It's a mistake to imagine that all drivers are arrogant, entitled, aggressive road-users. It's also a mistake to think that all cyclists are angels.
I spend a lot of time on Twitter arguing with drivers in support of cyclists, but I get no support from Cycle Twitter, because they all think I'm a troll for arguing with cyclists as well if and when I see fit. Take RLJ for example, cyclists all justify it on 'safety' grounds, but exept in very few cases, the reason isn't safety, it's that repeated stopping wastes an immense amount of energy:
It's conspicuous that RLJ is far more common in big cities than smaller towns, and it's not difficult to see that smaller towns offer more opportunity to leave the built up area when people feel the need to escape the frustration of stopping every few yards. I've pointed this out to cyclists numerous times, but it's usually ignored or lampooned. This is a major reason why I'm against another of cyclists' sacred cows: cycle paths. (see below)
If a vehicle in front of you is indicating, then you just don't overtake them on the side they are indicating towards
That depends how they got in front. I've seen drivers overtake, then signal and turn at the same time when their rear bumper is 6" in front of a cyclists wheel. The Highway Code tells drivers not to manoevre unless they can complete without forcing another road user to take avoiding action.
Would you attempt to pass, on the left, of a car, indicating a left turn, if you were in a car?
The roads and Highway Code aren't laid out in a way that expects motorists to do it:
You can't have it both ways. If cyclists campaign that they want paths that offer free passage up the nearside of roads without giving way at every side road, you can't then blame them for not giving way to the traffic at every side road. The reason cyclists aren't willingly going to give way is the amount of energy it wastes (see above), and separating cyclists from the main traffic flow increases the expectation among other road users that they should do so, as John Franklin points out in Cyclecraft.
I can see the way I take risks on cycle paths myself, and gamble at side roads rather than waste energy slowing down yet again, so it surprises me not at all when I see the research that shows they're less safe. That's why I'm against cycle paths/lanes. The problem is that people want what makes them feel better rather than what makes them safer.
Either give cyclists the RoW up the nearside
and enforce it, or don't lead them to think they have that right in the first place. Personally, I think the latter is the better option if you don't want to have to gamble your life on others respecting your rights.