Ubiquitin, interesting that you agreed with #2, yet added to #1 that there’s confusion about chumra vs. halachah. If the standards in a certain place are a certain way, going below those standards becomes a violation of halachah.
I’m not saying that’s necessarily the case here, but neither do we know that this was presented as halachah.
I think there’s no question that how someone wears their hair can be tzniusdik or untzniusdik (aside from the chiyuv for married women to cover it), and despite the fact that there’s no specific halachah addressing it, it can be a violation of tznius to wear the hair a certain way, depending on the minhag hamakom.
Someone may feel that a specific number is arbitrary, but there has to be a line somewhere.