>Facebook moved to penalize the researchers in part to remain in compliance with a 2019 data privacy agreement with the Federal Trade Commission, in which the company was punished for failing to police how data was collected by outside developers, Clark said. Facebook was fined a record $5 billion as part of a settlement with regulators.
That's a reasonable explanation for their action, right? Even if it's not 100% true, if you're a manager at Facebook, and the situation isn't 100% clear cut, you're still going to act, so you can show it as an example the next time the FTC tries to fine them.
And they did offer an alternative:
>Clark said Facebook offers targeting data sets for political ads, and has suggested the NYU group use that information.