But should that information ever have been publicly available? Someone else here linked to another instagram account publishing the same data, but that sure sounds like she didn't put it out there.

It's like saying that someone publishing your bank account balance or nude photos is fine, because someone once stole that data and released it on the internet.

Why is that true? Especially with such "must have been" certainty?

Or is "publicly available" used here to include data breaches and data sold by gray area data brokers? If this is your point then what would qualify as private information ? If this isn't your point

Indeed. <plays very small violin>.