"I think for the reality of this case it has to do with the law as it existed at the time of the accident."
I agree, that's true. However, for us on here, it can be beneficial to discuss the merits and potential changes of the law. It makes for interesting conversation about the law and how it could be better. After all, if we're strictly limited to the case there's no point in any of this discussion since we aren't the ones involved in it or deciding it.
You mention "dangerous" several times. We would need to define that. I'm sure there's some case law on that somewhere. My guess is it's highly debated and variable based on the circumstances of the case and opinions of the judge/jury. Especially when it comes to where the line is drawn on acceptable level of danger. This would also need to investigate contributory negligence. For example, the sidewalk may have been safe for the legal uses of the sidewalk but dangerous for the illegal use of scooters.
You also mentioned zoning. This is great! Most city codes require specific upkeep and allow for some variance. For example, some localities allow for a half inch difference in height of two adjacent pavings. I didn't see any pictures or measurements in the article, nor mention of the city's sidewalk code. But this is a highly pertinent area to investigate.