Not being a legal scholar, I won’t make a distinction between felony and misdemeanor.
What I will say is that just as computers are a force-multipler for getting important stuff done, they are also a force-multiplier for causing harm. As the old saying goes: “to er is human, to really foul up requires a computer”.
This leak did not endanger just one or two people, which would be bad enough, but 4000. Even if the remedy is limited to a fine sufficient for each affected person to change their names and address, it is still a more serious harm than almost anything normal intuition will help with because of how many were involved.
I wish that being in the sex industry was socially neutral for men and women and that nobody would be assaulted or insulted for it. I don’t know why that isn’t the case already, but I do recognise that it isn’t — and given that it isn’t, this leak is still extremely likely to result in someone getting hurt.