I disagree with you on several points. First of all, having problems with your car, does not in any way mean that the person copuld not drive the car properly or safely. stuff happens.
I am nominating the person ahead of me in the left-turn-arrow governed lane earlier today. The light turned green. They lurched forward a few feet - so they obviously saw it - and then stopped. There was nothing in the road that would have caused them to pause.
I honked a lot and they finally moved.
I'm sorry, but I would call you the SS in that situation. The way you described it, it sounds like they were in a stick. If they were new to it, or if something was wrong, it's very easy to have it stall after lurching forward a little like that. You "honking a lot" made it no easier on that driver trying to get going again. I was always so nervous while learning to drive a stick that I would have a driver react that way to me. A little patience and giving the other person the benefit of the doubt goes a lot longer than laying on your horn.
Assuming that guess is correct: the only SS in this situation was the person who couldn't drive a manual car properly or safely, yet still thought she was entitled to go out on the road and put other road users at risk because of it.
It absolutely horrifies me that people are allowed out on the road while not in full control of their vehicles. If you don't know how to use the clutch you are not in full control.
Second of all OP was SS for honkin a lot. Honking, when not to prevent an immediat danger (and in case of imediate danger you usualy do not have the time and reactionspeed to honk) or a modest honk for a person stopped at a green light, is unnecesary and SS. I am personaly of the opinion that the horn is one of the most useless and most abused features on cars.
I had, in fact, previously pointed out that it was highly unlikely that the person was having "problems with their car," as far as stalling due to not knowing how to drive a manual, as it was fairly obvious that they deliberately braked rather than stalled, especially since they were driving a vehicle that does not come with a manual transmission option.
The traffic signal in question is fairly short - so a "lot" of honking was maybe 10-15 seconds of me tapping the horn repeatedly, rather than laying on it - I don't use my horn very frequently, so perhaps my standards for "honking a lot" are a bit different than what people think when they read that.
The time to make a decision about which way you are traveling is prior to entering the turn lane, not after you've sat through a cycle of the light and started moving forward on the green arrow. The decision to allow your own poor planning or lack of information to impede the flow of traffic is SS. They had moved forward enough to not just impede the flow of the turn lane, but also enough to be sticking out into the crossing lane of traffic. It is fairly within the bounds of etiquette for using the horn to apply it in the fashion that I did - to get a single driver to move on their traffic signal.