Nyt article said anything over ten stories wad supposed to have sprinklers. Of course I am not an expert on these matters.
Commercial and residential buildings have different codes and it even explicitly says in the article that 'office buildings over ten stories' so i suspect that did not apply to this structure.
I doubt the building wasnt constructed to code. It would have had to pass a final fire inspection before being granted a certificate of occupancy and missing sprinklers are hard to ignore. It also wouldnt surprise me to find out renovations were conducted in a manner that avoided bringing the entire building up to code (typically required if over 50% of the structure is renovated after the code change even if done piecemeal).
I saw this practice all the time during my short architectural stint, including at some world renowned Universities. "Nope we cant do anymore updates to this dorm. If we do we'll have to bring the whole thing up to current fire code and we dont have the money for it."
"Make sure to bring the fire marshal in through the north entrance so he doesnt walk past these code violation areas"